The death toll from a double bomb attack targeting Shi'ites visiting a pilgrimage site in Damascus has climbed to 74, the Syrian Observatory for Human Rights reported on Sunday.

Most of the dead in Saturday's attack were Iraqi Shi'ites who were going to visit a cemetery near the Old City of Damascus.

There has been no claim of responsibility. The Hezbollah-run al-Manar TV station said it was carried out by two suicide bombers.

A roadside bomb detonated as a bus passed and a suicide bomber blew himself up in the Bab al-Saghir area, which houses several Shiite mausoleums that draw pilgrims from around the world.

Source: b'Shattered glass window of a bus at one of the sites / Source: Reuters'

Shiite shrines are a frequent target of attack for Sunni extremists of Al-Qaeda and the Islamic State group (IS), not only in Syria but also in neighbouring Iraq.On December 16 a seven-year-old girl wearing an explosive belt blew herself up outside a police station in Midan district, wounding three police officers.

Syrian President Bashar al-Assad has been supported in the country's war by Shi'ite militias from various countries, including Iraq, Afghanistan and Lebanon.

(With inputs from Reuters and AFP. Feature image source: Reuters)