Andrew Testa / Panos Pictures for NBC News

Father Nizar Semaan gives Holy Communion at Holy Trinity church in the Brook Green area of London.

LONDON -- Rana stepped out of church in Baghdad in December 2006 to find an envelope wedged against her car windshield. Inside was a bullet -- a message that meant she and her family were next on an assassin’s list. 

They fled the city the next day, leaving behind a business, a home -- everything.  

"I didn't like Saddam Hussein, but he didn't bother the Christians," said Rana, 29, after a church service in London. "He was a dictator. When he went, the gangs came from everywhere."

Rana isn’t alone: Bombings, kidnappings and generalized violence unleashed by the 2003 U.S.-led invasion of Iraq that toppled Hussein caused hundreds of thousands of Christians to flee their homeland.

While there is no centralized source of information on the number of Christians who have left Iraq, it is estimated that there were 2 million there in the 1990s. That number has fallen to between 200,000 to 500,000 today, according to church leaders.

 Rana, who like others interviewed would not give her last name because of fear for the safety of relatives still in Iraq, is now part of a congregation that worships at Holy Trinity Brook Green, a Roman Catholic church in West London.

The congregants -- Syriac Catholics whose services are conducted in Aramaic, the language spoken by Jesus -- are part of the estimated 2,500 Iraqi Christians thought to live in the U.K. 

In a pew near Rana sat Wasseem, a 26-year-old who arrived in the U.K. five months ago. The murder of his friend Rariq haunts him, Wasseem said through a translator. Rariq, also a Christian, was a driver for American forces in Baghdad and was kidnapped on his way to meet Wasseem. Rariq’s dismembered body was returned to his family five days later.

Wasseem received a handwritten death threat himself. Terrified, he decided to stay in his village in northern Iraq, he said. While safe, the predominantly Christian area offered no jobs, and he soon fled the country.

Extremists haven't targeted only individual Christians and their families. On Oct. 31, 2010, gunmen stormed Our Lady of Salvation Church in Baghdad during Sunday Mass, taking more than a hundred hostages. When security forces tried to free those held, the attackers detonated explosives. At least 58 people were killed, including two priests.

Related video: Baghdad church siege has bloody end  

A singer at Holy Trinity Brook Green lost her father in the bombing. Rev. Nizar Semaan, chaplain to the Syriac Catholic  community in the U.K., knew both of the murdered priests well. 

"They were very courageous people. It is not easy to do their job. And not easy to be a martyr," he said. 

Andrew Testa / Panos Pictures for NBC News

Iraqi children make up the choir at the London church.

Semaan’s support for Christians who have fled to the U.K. goes beyond the spiritual. 

"I try to help them find accommodation, I ask people to help in any way," he said.  "I call people to help them find a job."

Semaan said that he and his fellow priests refused to contemplate the extinction of the Christian community in Iraq, despite its falling numbers.

"Christianity can flourish again. It will grow back as an important part of the region," he said. 

Warina, who also attends Mass at Holy Trinity, is more downbeat. Like many of her fellow worshipers, she said life for Christians was better under Saddam Hussein.

"Our neighbors were Muslims. Our relations were friendly. We would visit them," said the dentist who fled Iraq in 2007. "Now it is just fighting. There are lots of churches and monasteries and places to worship in Baghdad -- but they are all empty."

"We love Iraq. It's our country, the origin of Christianity. But it is not safe," she added.

As Christians, Warina said, they are doubly vulnerable -- not only are they a minority, but they are perceived by some as having colluded with the invading American forces.

"After Saddam's death, people turned on Christians because they think the Christians encouraged the Americans to come to Iraq. Month after month, more and more are killed," she said.

Still, Semaan said he thinks a newly elected Pope Francis will act to support his threatened community.

"The pope will see the persecution and he will take care of us. He will not forget the church in the Middle East," Semaan said. "He is not a politician and he has no army, but he has good will and can encourage dialogue and maybe this can bring about a better situation."

Besides, Iraq needs its Christians, Semaan added.

"The Middle East without Christians would be a country without light," he said. "The future would be very dark." 

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Then and now: Rephotography shows Iraqi sites 10 years after Saddam

Reuters

This still image taken from video posted on a social media website on Saturday purportedly shows Saddam Hussein's former deputy and top aide Izzat Ibrahim al-Douri.

BAGHDAD -- A video posted online Saturday purports to show the highest-ranking fugitive member of Saddam Hussein's ousted regime lashing out against Iraq's Shiite-led government.

It was not possible to verify the authenticity of the video or determine when it was made.

The man in the video, which was posted on a website linked to Saddam's now-outlawed Baath party, was introduced as Izzat Ibrahim al-Douri. He bore a striking physical resemblance to the former Saddam deputy. He noted that nine years had passed since the 2003 U.S.-led invasion, suggesting the video was made recently.

The man resembling al-Douri sat in a Saddam-era uniform in front of the old Iraqi flag, flanked by a group of bodyguards, just as he did when delivering speeches in the past.

Al-Douri was the deputy head of Iraq's Revolutionary Command Council under Saddam, a Sunni who was toppled after the U.S.-led invasion in 2003. He took over the Baath Party leadership after Saddam was executed in 2006.

'Sounds of danger'
The man criticized Iraq's Shiite-dominated government, led by Prime Minister Nouri al-Maliki, and what he said was meddling by neighboring Shiite powerhouse Iran.

"Everyone can hear the sounds of danger echoing daily and threatening this country," he said during the hour-long address, adding that al-Maliki's Dawa Party "has announced Iraq as the Shiite capital, and called on all Arab leaders to surrender to this reality."

Al-Douri has been reported dead or captured more than once in the past. He has not been seen in public since the U.S.-led invasion, though audio tapes purporting to be from him have been released. His whereabouts are not known.

Archival video from 2005: Saddam top deputy al-Izzat dead?

Al-Douri is believed to have played a key role in financing Sunni insurgents seeking to undermine Iraq's post-Saddam government.

$10 million reward
After the invasion, al-Douri was ranked sixth on the U.S. military's list of 55 most wanted Iraqis and a $10 million reward was offered for his capture. He was the "king of clubs" in the deck of playing cards issued by the U.S. to help troops identify the most-wanted members of Saddam's regime.

Baathists were banned from politics after the 2003 invasion, but the government says many former party members have organized into insurgent groups resisting the rise to power of the Shiite majority following the fall of Saddam.

Maliki ordered the arrest of hundreds of former Baathists last year just before the last American troops left the country, causing a crisis that threatened to unravel a fragile power-sharing deal among Sunni, Shiite and Kurdish blocs.

Ali al-Moussawi, a media adviser for al-Maliki, said the tape is meant to "boost the morale of the terrorists."

Jassim Mohammed / AP file

Izzat Ibrahim al-Douri is seen during a ceremony in Baghdad, Iraq, on Dec. 1, 2002.

"Al-Douri wants to spread terrorism and sectarian violence under the pretext of resistance," he said. "This will not affect the work of the government or the political process."

Al-Moussawi said al-Douri is still a wanted man, but that he doubts that al-Douri is still in Iraq because his need for extensive medical care in a well-equipped clinic would make it impossible to hide.

Wax museum spurs sticky situation in Iraq

Meanwhile, a bomb hidden in a plastic bag blew up on a minibus, killing two passengers and wounding nine in Baghdad's commercial heart of Karrada on Saturday, according to police and hospital officials. They spoke on condition of anonymity because they were not authorized to brief the media.

Deadly attacks have declined in Iraq in recent weeks, but dozens are still killed every month. March saw the lowest monthly toll for violent deaths since the 2003 U.S.-invasion.

The Associated Press and Reuters contributed to this report.

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Sabah Arar / AFP - Getty Images

Iraq's former premier Iyad Allawi during a press conference in Baghdad in October, 2009.

A leading Iraqi politician has accused the country's prime minister of acting like Saddam Hussein in trying to silence opposition, saying he risks provoking a new fightback against dictatorship.

Iyad Allawi -- a former prime minister who leads the Sunni-backed Iraqiya bloc -- also claimed the United States had pulled out its troops "without completing the job they should have finished."

Allawi said that the current premier, Nuri al-Maliki, had used fabricated confessions to demand the arrest of the country's Sunni Muslim vice president, Tareq al-Hashemi.

Al-Hashemi, who has taken refuge in Iraq's autonomous Kurdish region, denies allegations he ordered bombings and shootings against his opponents. The move against him, on the very day U.S. troops left the country, threatens to upset a balance among Shiite, Sunni and Kurdish factions.

Speaking to Reuters two days after the final departure of the U.S. forces that ended Saddam's Sunni-dominated rule, Allawi called for international efforts to prevent al-Maliki, who is a Shiite, from provoking renewed sectarian warfare of the kind that killed tens of thousands in the years after Saddam fell in 2003.

"This is terrifying, to bring fabricated confessions," Allawi said shortly before leaving the Jordanian capital Amman to return to Iraq. "It reminds me personally of what Saddam Hussein used to do where he would accuse his political opponents of being terrorists and conspirators."

• Arrest order for Sunni VP in Iraq raises tensions

"We fear the return of dictatorship by this authoritarian way of governing. It's the latest in a build-up of atrocities, arrests and intimidation that has been going on a wide scale," said Allawi, who comes from the Shiite Muslim majority but who has drawn support heavily from disaffected Sunnis.

As prime minister for 10 months under U.S. occupation in 2004 and 2005, Allawi was accused of revealing an authoritarian streak himself. He later led the Iraqiya bloc to first place in last year's parliamentary election but ended up joining a coalition headed by al-Maliki, who retained the premiership.

• For 'the Sheik,' US pullout is cause for alarm

He said he would now try to unseat the prime minister in the legislature: "We have to make a move to bring about stability to the country by trying to find a substitute to Maliki through parliament," said Allawi, who repeated allegations that Shiite Iran is seeking control in Iraq now that U.S. forces have left.

"Maliki has crossed all red lines and Iraq is now facing a very, very serious and very difficult situation," he said.

'Very heart of democracy'
"We are watching events unfolding which are aimed at the very heart of democracy and stability," he added. "The Americans have pulled out without completing the job they should have finished. We have warned them that we don't have a political process which is inclusive of all Iraqis and we don't have a full-blown state in Iraq."

"We want to resolve issues between Iraqis in a peaceful way and we want to bring stability. Iraqis should fill the vacuum, rather than anybody else," Allawi said, in a reference to his view Iran is intent on filling a vacuum left by U.S. troops.

Iraq sits on a sectarian, Sunni-Shiite faultline that is generating conflict throughout the region, notably between Iran and Sunni-ruled Arab states like Saudi Arabia. While the overthrow of Saddam in Iraq bolstered Shiites, the uprising against Iran's Syrian ally President Bashar al-Assad could lead to power in Damascus shifting toward Syria's Sunni majority.

"The rise of sectarianism is already there," Allawi said. "We are witnessing the beginning of it and the influences of what is happening in the region is only adding fuel to the fire. My fear is that the Iraqi people will lose faith in the political process and sectarianism will prevail.

"Unless the international community and the region get involved and unless sense prevails, Iraq is heading towards a very big conflict."

Also Tuesday, al-Hashemi told a televised news conference that he has not committed any "sin" against Iraq and also described the charges as "fabricated." He accused al-Maliki of being behind a plot to smear him and declared that efforts at national reconciliation had been blown apart.

"I'm shocked by all these things," al-Hashemi told reporters in the northern city of Irbil. "I swear to God that al-Hashemi didn't commit any sin or do anything wrong against any Iraqi either today or tomorrow and this is my pledge to God."

He said the arrest warrant was a campaign to "embarrass" him. He blamed al-Maliki, although he did not say specifically what he believed the Shiite premier had done.

"Al-Maliki is behind the whole issue. The country is in the hands of al-Maliki. All the efforts that have been exerted to reach national reconciliation and to unite Iraq are now gone. So yes, I blame al-Maliki," he said.

The Iraqi prime minister effectively runs the Interior Ministry, where the charges originated.

Reuters and The Associated Press contributed to this report.