A group that monitors Syria's civil war said a car bomb exploded on Monday in a southern district of Damascus which is home to Syria's holiest Shi'ite Muslim shrine, but Hezbollah's Al Manar TV denied any blast took place.
The British-based Syrian Observatory for Human Rights said the car bomb went off near a checkpoint used by the Syrian army and its allies, which include Lebanese Hezbollah and other Shi'ite militias.
There was no immediate mention of the blast on Syrian state media, which normally reports bomb attacks in government-held areas.
The area has been targeted several times by deadly bombings this year, most recently in June with an attack claimed by Islamic State.
The Observatory said initial reports indicated there were some casualties in Monday's attack, but not among civilians.
The Sayeda Zeinab shrine is a magnet for thousands of Iraqi and Afghan Shi'ite militia recruits who go there before being sent to frontlines, where they fight against Sunni rebel groups trying to topple President Bashar al-Assad.