Three armed men have been killed and one wounded after they attacked
the US embassy in Damascus in what Syria has called a terrorist
operation.

The men were chanting religious slogans as the approached the embassy compound on Tuesday and, according to Syrian television, they attempted to blow up a car outside.

A Syrian official said all US diplomats are safe while a witness said at least one Syrian security guard has been killed in the fighting.

Syrian security forces sealed off the Rawda area after heavy gunfire erupted.

The district also houses security installations and the homes of top government officials.

There was no word on the identity of the attackers, but Syrian forces clashed with Islamist fighters several times last year, usually in raids to arrest them.

The interior minister described the attack as "a terrorist operation" and told Syrian television that "investigations are underway to find out more details".

Britain's ambassador to Syria, Peter Ford, told CNN that the attack did not appear to be a "major al Qaeda-like operation, but an operation by a small group".

The US State Department confirmed there had been an attack but said  it "appears to be over".

"We can confirm reports of an attack on our embassy in Damascus by unknown assailants. The event appears to be over. Local authorities have responded and are on the scene," a US state department spokesman, Curtis Cooper, said.