An explosion tore through the car park outside Syria's highest court in central Damascus on Thursday, torching at least 20 cars, a Reuters witness said, but it was not immediately known if there were any casualties.

The building appeared intact as firefighters doused burning cars with water and ambulances arrived at the scene, with state television describing the attack as a "terrorist explosion".

The car park is used by lawyers and judges working at the Palace of Justice, Syria's highest court.

An uprising against President Bashar al-Assad that began with peaceful street protests 16 months ago evolved largely into an armed conflict after his forces continually attacked demonstrations. Rebel fighters are increasingly targeting symbols of a state they see as oppressive and autocratic.

On Wednesday, rebels stormed a pro-Assad Syrian television channel and militants have also targeted police and security personnel barracks. In April militants fired rocket-propelled grenades at the Central Bank building. - Reuters