Updated at 6:30 p.m. ET: The head of Lebanon's Shi'ite militant group Hezbollah on Sunday called for nationwide protests over a film about the Prophet Muhammad, saying that the United States must be held accountable for creating strife between Muslims and Christians.

The call came as Western embassies across the Muslim world remained on high alert Sunday as protests continued from London to Lahore. Violence left one dead in Pakistan.

"We call for protests tomorrow in the southern suburbs (of Beirut) at 5 o'clock," Hezbollah Secretary-General Sayyed Hassan Nasrallah said in a televised speech. "Muslims and Christians must remain vigilant in order to refrain from sliding towards strife. Those responsible for the film, starting with the U.S., must be held accountable."

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"All these developments are being orchestrated by U.S. intelligence," he said, adding that the U.S. government was using the excuse of freedom of speech in order to justify the continued broadcast of the film.

Nasrallah also called for demonstrations around Lebanon, including the southern coastal town of Tyre on Wednesday and the northern town of Hermel on Sunday.

The video, circulating on the Internet under several titles including "Innocence of Muslims", portrays Mohammad as a womanizer and a fool. In one clip posted on YouTube, Mohammad was shown in a sexual act with a woman.

Many Muslims consider any depiction of the prophet as offensive and fury about the film tore across the Middle East this week, with protesters attacking U.S. embassies and burning American flags.

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The U.S. ambassador to Libya, Christopher Stevens, and three other Americans were killed in Benghazi, Libya, last Tuesday. At least nine people were killed in protests in several countries on Friday, but protests subsided over the weekend.

Pope tells Christians in Beirut: 'Be peacemakers'

Nasrallah's speech came a few hours after Pope Benedict left Lebanon for the Vatican, ending a three-day tour in which he urged Arab leaders to serve justice and peace.

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Nasrallah, head of the strongest armed force in the country, said in a statement last week that he supported the visit.

Western diplomatic missions were on edge Sunday. Germany followed the U.S. lead and withdrew some staff from its Sudan embassy, which was stormed on Friday.

Around 350 people chanted slogans at a rally outside the U.S. Embassy in London; a small group of protesters burned a U.S. flag outside the U.S. Embassy in the Turkish capital, and in Pakistan there were small protests in more than a dozen cities.

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One person was killed when unidentified people opened fire at a protest in the southern city of Hyderabad, police said.

One person was killed and dozens of people when anti-American protesters tried to storm the American Consulate in the southern port city of Karachi and clashed for several hours with the police and paramilitary troops on Sunday evening, rescue workers and police officials said, The New York Times reported.

Pakistani officials had increased security in all major cities before Friday Prayer services and until Sunday, calm had prevailed. The American Embassy here said in a message posted Sunday evening on Twitter that “all American personnel are safe and accounted for at U.S. Consulate, Karachi.”

The United States has deployed a significant force in the Middle East to deal with any contingencies and rapid deployment teams were ready to respond to incidents, he said.

The foreign minister of Egypt, where hundreds of people were arrested in four days of clashes, assured Secretary of State Hillary Clinton that U.S. diplomatic grounds would be protected.

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The attack that killed four Americans at the U.S. Consulate in Benghazi, Libya, apparently began as a spontaneous protest against an anti-Islam film before turning violent, Susan Rice, U.S. ambassador to the United Nations, said Sunday.

Rice, appearing in NBC’s “Meet the Press,” said she was citing preliminary information and that the FBI was investigating the Tuesday night attack that killed the U.S. ambassador to Libya, Chris Stevens, and three others.

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A wave of protests and violence has swept across the Middle East and elsewhere in the Muslim world over an obscure, amateurish movie called "Innocence of Muslims" that depicts Muhammad as a fraud, a womanizer and a pedophile. Anti-U.S. protests in 20 countries led the Pentagon to dispatch elite Marine antiterrorism teams to Libya and Yemen and to position two Navy warships off Libya's coast.

Meanwhile, the State Department ordered all nonessential U.S. government workers and their families out of Sudan and Tunisia. In Lebanon, protesters torched an American fast-food restaurant. Even as tensions appeared to ease over the weekend, al-Qaida's most active Mideast branch was calling for further attacks on U.S. embassies.

"There's no question, as we've seen in the past with things like 'The Satanic Verses,' with the cartoon of the Prophet Muhammad, there have been such things that have sparked outrage and anger and this has been the proximate cause of what we've seen," Rice said.

“What happened in Benghazi was in fact initially a spontaneous reaction to what had just transpired hours before in Cairo, almost a copycat of the demonstrations against our facility in Cairo, prompted by the video,” Rice said.

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Protesters in Cairo had breached the walls of the U.S. Embassy and tore down the American flag.

In Benghazi, Rice told “Meet the Press” host David Gregory, “Opportunistic extremist elements came to the consulate as this was unfolding, they came with heavy weapons, which unfortunately are readily available in post-revolutionary Libya, and it escalated into a much more violent episode.”

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There was “no actionable intelligence” that the attack in Benghazi was imminent, Rice said. The attack overwhelmed security in place at the consulate, she said.

Rice’s comments came a day after Libyan President Mohammed Magarief told NBC News that “foreigners” were involved in the planning and execution of the attack.

He expanded on the assertion Sunday, saying on CBS’ "Face the Nation" that about 50 people, not all Libyans, have been arrested in connection with the Benghazi attack, which he said was planned by al-Qaida-linked foreigners, some from Mali and Algeria.

Magarief said there was little doubt the assault was planned rather than a spontaneous reaction to the video, as came on the 11th anniversary of the 9/11 terrorist attacks in the U.S.

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He said the security situation in Libya remained "difficult" for Americans, as well as for Libyans. The United States wants the FBI to investigate the consulate attack, but Magarief said it may be too soon to send in investigators.

"It may be better for them to stay away for a little while until we do what we have to do ourselves," he said.

Rice told "Meet the Press" that the U.S. is working with authorities in Libya, which has received $200 million in U.S. aid since 2011, to bring to justice those responsible for the attack.

This article includes reporting by Reuters.

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Libyans and "foreigners" carried out the attack on the U.S. Consulate in Benghazi that killed the U.S. ambassador and three other Americans, Libyan President Mohamed Magariaf told NBC News on Saturday.

Magariaf's interview with NBC's Ayman Mohyeldin was the first time any Libyan official has said foreigners were involved in the planning and execution of the Tuesday night attack that took the lives of U.S. Ambassador Christopher Stevens and three others.

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"We have assumptions and we have some information, and all that information we have now leads to the same direction about the perpetrators, the criminals," Magariaf told NBC in the interview aired on "Nightly News" Saturday.

Foreigners were involved in the planning and execution of the attack, he said.

Magariaf did not identify where the foreigners came from but said he was sharing details with U.S. officials.

Many people reportedly have exploited Libya's security vacuum and loopholes, Libyans have told NBC.

Magariaf also added that Libyan authorities have suspects in custody.

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Earlier Saturday, a security official told Reuters that Libyan authorities identified 50 people involved in the attack.

"We have names and we know who they are, but there could be more," said Abdel-Monem Al-Hurr, spokesman for Libya's Supreme Security Committee.

"Four have been arrested. Some of the others may have escaped via Benghazi airport, maybe to Egypt, but this not confirmed," Al-Hurr said. "We have given their names to all of the Libyan border entry points."

This article also includes reporting by Reuters.

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Updated at 4:15 p.m. ET:KHARTOUM -- Sudan has rejected a U.S. request to send a platoon of Marines to bolster security at the U.S. embassy outside Khartoum, the state news agency SUNA said on Saturday.

The U.S. ordered all family members and non-emergency personnel out of Khartoum as well as Tunis, Tunisia, posts, State Department spokesperson Victoria Nuland said Saturday afternoon. The State Department also issued travel warnings to U.S. citizens in both countries.

Earlier Saturday, a U.S. official, who spoke on condition of anonymity because the official was not authorized to disclose details on the troop movement, said Sudan's objection held up the deployment of 50 Marines. A U.S. official said the Marines had already set off for Khartoum but had been called back pending further discussions with Sudan.

Nuland earlier Saturday didn't speak about the Marines but acknowledged Sudan had "recommitted itself both publicly and privately to continue to protect our Mission, as it is obligated to do under the Vienna Convention."

"We are continuing to monitor the situation closely to ensure we have what we need to protect our people and facility," Nuland said.

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On Friday, around 5,000 people protested against a film that insults the Prophet Muhammad, storming the German embassy before breaking into the U.S. mission.

They also attacked the British embassy. At least two people were killed in clashes with police, according to state media.

In Tunis, four people were killed and 46 were wounded, the Tunisian government said, after police gunfire near the U.S. Embassy in the North African city that was the model for last year's pro-democracy revolutions.

Police fought hundreds of protesters who smashed windows, hurled petrol bombs and stones at police from inside, and started fires in the embassy and to a gym and a neighboring American school. A Reuters reporter saw police open fire on protesters forcing their way into the embassy building.

A U.S. official told Reuters on Friday that Washington would send Marines to Sudan to improve security at the embassy located outside Khartoum.

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"Sudan is able to protect the diplomatic missions in Khartoum and the state is committed to protecting its guests in the diplomatic corps," Sudanese Foreign Minister Ali Ahmed Karti told SUNA.

Sudan beefed up security at some missions on Saturday. A riot police truck was parked in front of the deserted German embassy, which protesters had set on fire on Friday. An Islamic flag raised by the crowd was still flying. Three officers manned the main gate.

More than 20 police officers were sitting in front of the U.S. Embassy.

The film, which depicts Muhammad as a womanizer and charlatan, was made in the United States, and Muslim outrage has led to crowds assaulting U.S. diplomatic missions in a number of Arab countries.

Sudan has also criticized Germany for allowing a protest last month by right-wing activists carrying caricatures of Muhammad, and for Chancellor Angela Merkel's award in 2010 to a Danish cartoonist who had depicted the prophet, triggering unrest across the Islamic world.

President Omar Hassan al-Bashir has been under pressure from Islamists who feel the government has given up the religious values of his 1989 Islamist coup.

The Sudanese government had called for protests against the film, but peaceful ones. President Barack Obama's administration said it had nothing to do with the movie, which is little more than an amateurish video clip and appears to have been made in California.

This article includes reporting by NBC News' Catherine Chomiak, Reuters and The Associated Press.

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Updated at 3:20 p.m. ET: President Barack Obama on Saturday rejected any denigration of Islam, but insisted there was no excuse for attacks on U.S. embassies as angry protests over an obscure, anti-Muslim film spread to Australia.

"I have made it clear that the United States has a profound respect for people of all faiths," Obama said in his weekly radio address.

"Yet there is never any justification for violence .... There is no excuse for attacks on our embassies and consulates,” he added.

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Anti-American protests have swept the Muslim world in response to the film, which insults the Prophet Muhammad.

Libya president: 'Foreigners' involved in consulate attack

The death toll as a result of violence during protests in the Middle East and North Africa Friday rose from seven to nine with Tunisian officials saying four people -- rather than two as stated earlier -- died there. Three were killed by gunfire and the other died after being hit by two police cars, a senior hospital official told Reuters.

An attack on the U.S. Consulate in the Libyan city of Benghazi killed U.S. Ambassador Christopher Stevens and three others this week.

A day after Obama led a somber ceremony marking the return of the bodies of the Americans killed in Libya, Obama acknowledged that a surge of anti-American violence in the Middle East is disturbing.

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The Pentagon had said it was sending Marines to beef up security at the U.S. Embassy in Sudan, following similar reinforcements to Libya and Yemen. But on Saturday, Sudan rejected the U.S. request to send a platoon the embassy in Khartoum.

"Sudan is able to protect the diplomatic missions in Khartoum and the state is committed to protecting its guests in the diplomatic corps," Foreign Minister Ali Ahmed Karti told SUNA, the state news agency.

Protesters on Friday entered the embassy grounds.

The Libyan attack and theU.S.-directed outrage have raised questions about Obama's handling of the so-called Arab Spring, a series of revolutions that have unseated entrenched authoritarian governments.

Related: At least seven reported killed in protests

The turbulence in the Middle East has had ripples in a tight U.S. presidential election, with Obama's Republican challenger Mitt Romney saying Obama has weakened U.S. authority around the world.

However, Obama repeated a vow to bring the attackers of the U.S. Consulate in Libya to justice. "We will not waver in their pursuit," he said.

The president also said the turmoil should not deter U.S. efforts to support democracy in the region or elsewhere.

"Let us never forget that for every angry mob, there are millions who yearn for the freedom, and dignity, and hope that our flag represents," he said.

The protests over the anti-Islam film, "Innocence of Muslims," continued Saturday, spreading to Australia where authorities seemed taken by surprise as more than 400 demonstrators gathered outside the U.S. Consulate in Sydney.

Some of the chanting protesters carried placards reading "Behead all those who insult the Prophet."

Several streets, usually thronging with weekend shoppers, were blocked off by police as the protest grew. Police, many wearing anti-riot equipment and some on horseback, used dogs and chemical sprays as they tried to control the protest.

Reuters Television pictures showed one policeman with a head injury being led away by colleagues. Police later said six officers had been injured and eight protesters arrested. A spokesman for paramedics said there were no serious injuries. 

A Muslim leader addressed the protesters in a park, calling for calm.

In Egypt, the interior minister said he would restore calm after a 35-year-old protester was killed and dozens of people were injured in clashes overnight.

The authorities closed the street leading to the U.S. Embassy where the demonstrators had spent four days throwing rocks and petrol bombs at police.

A Reuters reporter saw police push several young men into trucks. Two of the men looked bruised and one was stripped down to his underwear.

Police formed cordons on roads into Tahrir Square near the U.S. mission and plain-clothes officers wielding sticks frisked passers-by. The square, the focus of last year's popular uprising that overthrew President Hosni Mubarak, was strewn with garbage and a torched vehicle was towed away.

"Our presence here is to clear the square of people who are breaking the law," Interior Minister Ahmed Gamal el-Din said as he inspected the area. "We must preserve the square as a symbol of the revolution. That is the aim of our operation."

He said measures would be taken to ensure "those breaking the law" do not return.

The protesters said they wanted to expel the U.S. ambassador to punish Washington over the low-budget film. It portrays the Prophet Muhammad as a womanizer and religious fake. U.S. Secretary of State Hillary Clinton has called the film "disgusting and reprehensible."

Egypt's state news agency said 27 people were injured on Friday, which suggests more than 250 people have been hurt in the clashes since Tuesday, when protesters climbed the embassy's walls and tore down an American flag.

President Mohamed Morsi, an Islamist and Egypt's first freely elected leader, has to strike a delicate balance, fulfilling a pledge to protect the embassy of a major aid donor while delivering a robust line against the film to satisfy his Islamist backers.

In Sinai, militants attacked an international observer base close to the borders of Israel and Gaza, a witness and a security source said. Two Colombian soldiers were wounded, an official from the observer force said.

Many Muslims regard any depiction of the Prophet Muhammad as blasphemous. The film has provoked outrage across the Middle East and led to the storming of several U.S. missions in the region.

In Libya, authorities said they had made four arrests in the investigation into the attack on the U.S. Consulate in Benghazi on Tuesday that killed the U.S. ambassador and three other Americans.

Morsi has condemned the film, rejected violence and promised to protect diplomatic missions. His cabinet said Washington was not to blame for the film but urged the United States to take legal action against those insulting religion.

The United States has a large embassy in Cairo, partly because of a vast aid program that began after Egypt signed a peace deal with Israel in 1979. Washington gives $1.3 billion in aid a year to Egypt's army plus additional funds for government.

In Yemen, al Qaida urged Muslims on Saturday to step up protests and kill U.S. diplomats in Muslim countries and called the film denigrating Muhammad another chapter in the "crusader wars" against Islam.

"Whoever comes across America's ambassadors or emissaries should follow the example of Omar al-Mukhtar's descendants (Libyans), who killed the American ambassador," Yemen-based Al Qaeda in the Arabian Peninsula (AQAP) said.

"Let the step of kicking out the embassies be a step towards liberating Muslim countries from the American hegemony," it said in a statement posted on a website.

Reuters and The Associated Press contributed to this report.

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