Discuss as:

UN: Syria using fighter jets against rebels with tanks

For days the Syrian troops' weapons have given them the upper hand during key battles in Aleppo, but the rebels – now armed with powerful shoulder fired anti-aircraft missiles -- are preparing for a different kind of fight. NBC's Richard Engel reports.

Syrian fighter jets fired on rebel positions in the commercial capital of Aleppo on Wednesday, U.N. observers told The Associated Press, a development that could signal a significant escalation in the battle for control of the key city.

In a briefing on Wednesday, U.N. mission spokeswoman Sausan Ghosheh also said the United Nations had confirmation that the rebels now have heavy weapons of their own, including tanks.

On Tuesday, NBC News' Richard Engel reported from northern Syria that the rebels were now equipped with powerful shoulder-fired anti-aircraft missiles, which could narrow the gap between opposition fighters and the well-equipped forces of President Bashar Assad.

Amateur video reportedly from Aleppo, Syria, shows destruction in the city, a nighttime rebel rally along with the schoolyard execution of some pro-Assad military forces. NBCNews.com's Dara Brown reports. Editor's Note: This video contains graphic material that some viewers may find disturbing.

The U.N.'s Ghosheh expressed concern over the situation in the northern city of Aleppo, where rebels have been battling government forces for the past 12 days.

Residents face shortages as Syrian army hits Aleppo

She described "heavy use of heavy weapons, including tanks, helicopters, heavy machine guns, as well as artillery."

Earlier, Reuters reported that government combat aircraft and artillery pounded Aleppo late into the night as the army battled for control for the fifth day, where rebel fighters said troops loyal to Assad had been forced to retreat.

The battle for Aleppo, Syria's largest city, has become a crucial test for both sides in the 16-month-old rebellion against the Assad family's four-decade-long grip on power. Neither Assad's forces nor the rag-tag rebels can afford to lose if they hope to prevail in the wider struggle for Syria.


Rebels arrest a man who they claim to be a traitor at an old military base in Sicco village, near Aleppo, Syria, on Tuesday.

Forces opposing the government estimate that about 20,000 people have died during the rebellion.

Assad cites 'internal agents'
Assad also said Wednesday that foreign enemies were using "internal agents" to undermine the country's stability.

Thousands have fled Aleppo, driven out by heavy fighting.   NBC's Ayman Mohyeldin reports from one refugee camp along the Turkey Syria border, where some frightened civilians have ended up. 

Speaking to the army on the 67th anniversary of its founding, Assad said the armed forces are the "homeland's shield" against plots by criminal and terrorist gangs, using terminology the government often uses to describe the fight against the rebels.

He said the people see the army as a "source of pride" and a "defender of just causes."

The speech, which was carried by the state news agency but not broadcast on state television, was a rare comment from the president who has kept a low profile during recent fighting in the country's two main cities.

On the streets of Aleppo fierce clashes between rebel forces and Syrian troops continue. These pictures, filmed by opposition activists in the suburb of Salah al-Din, show the latest fighting in one of the key battlegrounds. ITV's Neil Connery reports.

Fighting in Christian neighborhoods
Also Wednesday, fighting reportedly broke out between Syria's army and rebel fighters in near two Christian neighborhoods in the heart of the country's capital Damascus for the first time since the uprising broke out.

The pro-rebel Syrian Observatory for Human Rights said that the firefight erupted early Wednesday on the outskirts of Damascus' Bab Tuma and Bab Sharqi, two traditional Christian districts of the city.

UN: 200,000 Syrians flee fierce fighting in Aleppo

"This is fighting in areas where it has not happened before. These are areas where the rebels have so far not had access," Observatory chief Rami Abdel Rahman told AFP news service.

While calm returned to the area later, the fighting underlined fears felt by many in the Christian community that they would be among the chief losers if the rebels were to overthrow Assads government.

NBC News staff, The Associated Press and Reuters contributed to this report. 

More world stories from NBC News: