A marine stands guard at the US embassy in Damascus Supporters of Syrian President Bashar al-Assad have broken into the US and French embassies in Damascus. A US embassy official told the BBC there had been physical damage there , but no-one had been injured. Windows were smashed and a Syrian flag raised.
Earlier, guards at the French embassy fired into the air to disperse a crowd.
The protests come days after the US and French ambassadors visited the central city of Hama, where a massive anti-government rally was held on Friday.
The separate visits - which both governments said were meant to express solidarity with the opposition - drew sharp criticism from Damascus.
Pro-government demonstrators have been taking part in protests outside both embassies for the past two days.
Human rights groups say at least 1,400 civilians and 350 security force personnel have been killed since demonstrations began in mid-March.
A US embassy official in Damascus told the BBC on Monday afternoon that the embassy had come under attack by a \"mob\".
The official said that the Syrian government had given assurances that they would provide adequate protection for the embassy.
But on this occasion, the authorities were slow to respond, he added.
Witnesses told the Associated Press news agency that the protesters had smashed windows and raised a Syrian flag on the compound.
They also wrote anti-US graffiti referring to the ambassador, Robert Ford, as a \"dog\", the witnesses said.
The US embassy official said that the real story in Syria was not the attack on the embassy, but the fact that the government continued to imprison, torture and kill citizens because they want to protest.
The attacks on the embassies coincide with a government-organised dialogue conference in Damascus that many opposition leaders are boycotting.
The meeting is discussing possible political reforms, which the government hope will bring an end to the four-month-old uprising.
The Syrian government denies targeting civilians, saying it is tackling armed groups.