|Protesters scale the US embassy in Damascus, Syria, in this photo from the social media network [Facebook]
Supporters of the Syrian government have stormed the US and French embassies in Damascus, prompting strong condemnation by the two countries' officials.
Witnesses describing Monday's assault said the attackers smashed windows and raised a Syrian flag at the US diplomatic compound and wrote anti-American graffiti referring to the US ambassador as a "dog".
A US official said the mob breached the wall of the embassy compound before being dispersed by Marine Corps guards.
No buildings were entered and there were no injuries to embassy personnel, but one of the office buildings was damaged and Syrian security forces were slow to respond, the official said.
The official further said the Obama administration will formally protest and may seek compensation for damage caused by the attack.
In-depth coverage of escalating violence across Syria
Following the embassy assault, the residence of the US ambassador, Robert Ford, was attacked by a mob.
Later, Hillary Clinton, the US secretary of state, said the Syrian leader had lost legitimacy.
"If anyone, including President [Bashar] Assad, thinks that the United States is secretly hoping that the regime will emerge from this turmoil to continue its brutality and repression, they are wrong," she said.
"President Assad is not indispensable and we have absolutely nothing invested in him remaining in power."
The state department had earlier said it would summon a senior Syrian diplomat to condemn the assault and demand that Syria uphold international treaty obligations to protect foreign diplomatic missions.
'Diversion' from protests
Al Jazeera's Rosiland Jordan, reporting from Washington DC, said that US authorities have accused Syria of using the embassy attacks "as a diversion from protests against Assad ... and simply will not work".
At around the same time the US embassy was targeted, security guards at the French embassy in Damacus had to fire into the air and use tear gas to drive back Assad supporters.
One witness said three protesters were injured when embassy guards beat them with clubs.
"Syrians demonstrated peacefully in front of the French embassy but they were faced with bullets," Hiam al-Hassan, a witness, said.
"[Syrian] security forces are supposed to protect or ensure the safety of our personal officers and of our buildings," a spokesperson for the French foreign ministry said.
Al Jazeera's Rula Amin, reporting from Beirut in neighbouring Lebanon, said that security in Syria is so tight that the protesters would not have been able to get so close to the embassies without approval from the government.
The mob attacks have occurred just days after the US and French ambassadors visited the opposition stronghold of Hama in central Syria.
The Syrian government called the visits to Hama interference in the country's internal affairs and accused the ambassadors of undermining Syria's stability.
Ford, the US ambassador to Syria, has of late harshly criticised the Syrian government's crackdown on the popular uprising.
He attacked the Syrian government on Sunday for allowing rallies by supporters while beating up anti-government demonstrators.
'We love you'
The pro-Assad demonstrations in Syria are known as "mnhebak", or "we love you".
"I have not seen the police assault a 'mnhebak' demonstration yet," Ford recently wrote on the embassy's Facebook page.
"On July 9, a 'mnhebak' group threw rocks at our embassy, causing some damage. They resorted to violence, unlike the people in Hama, who have stayed peaceful."
"And how ironic that the Syrian Government lets an anti-US demonstration proceed freely while their security thugs beat down olive branch-carrying peaceful protesters elsewhere", he said.
"I saw no signs of armed gangs anywhere not at any of the civilian street barricades we passed.
"Hama and the Syrian crisis is not about the US at all. This is a crisis the Syrian people are in the process of solving. It is a crisis about dignity, human rights, and the rule of law."