A suicide bomber targeted a mosque in central Damascus on Thursday, killing a senior pro-regime Sunni cleric, Syrian television reported, with a watchdog saying at least 15 people were killed.

"Senior cleric Dr Mohammed Saeed Ramadan al-Bouti was martyred in a terrorist suicide attack at the Iman Mosque in Mazraa in Damascus," the channel said, adding that there were reports of more dead and wounded.

The Syrian Observatory for Human Rights said at least 15 people were killed in the attack in addition to Bouti, with dozens more injured at the mosque in Mazraa district, just north of the city centre.

Syria's official Al-Ikhbariya television channel broadcast gruesome footage from inside the mosque, where dozens of bodies were strewn on the carpeted floor. Body parts including limbs and hands were scattered on the floor.

The footage showed emergency workers collecting corpses from inside the mosque and carrying them out in grey body bags.

A presenter on the channel said a suicide bomber had entered the mosque and blown himself up.

Bouti was the most senior pro-regime Sunni cleric in Syria, and his weekly addresses at Friday prayers were frequently broadcast live on state television.

After news of the attack broke, one state television station interrupted its regular programme to broadcast verses from the Koran, the Muslim holy book.