The shrine was allegedly where she was held captive by a Sunni caliph after her brothers, Hussein and Hassan, were killed in Karbala in modern-day Iraq.

The site has continued to attract pilgrims from Syria and beyond, particularly Shiites from Iran, Lebanon, Iraq and the Gulf, throughout the conflict.

The complex was rebuilt in 1990 and features a glistening gold onion-shaped dome, intricately decorated blue tiles covering its facade and two freestanding minarets.

It has often been the scene of bitter fighting between Sunni rebels and the regime and has also been used to justify the presence of Shiite militias from Lebanon and Iraq, alongside the Syrian army.

Early on in the conflict, powerful Lebanese Shiite movement Hezbollah cited the threat to Sayyida Zeinab as the motivation for its intervention on the side of President Bashar al-Assad.

Syria is a Sunni-majority country but power for the past half century had been in the hands of Assad's Alawite clan, an offshoot of Shiite Islam.

As Syria's war dragged on and jihadist groups became more prominent, Shiites have come under increasing attack because Sunni extremists consider them to be heretics.

The area around the Sayyida Zeinab shrine, heavily secured with regime checkpoints set up hundreds of metres (yards) away to prevent vehicles from approaching, has been targeted many times.

On January 31, bombings claimed by IS killed at least 70 people and wounded dozens more.

Almost a year earlier, in February 2015, two suicide attacks killed four people at a checkpoint near the shrine.

Also that month, a blast ripped through a bus carrying Lebanese Shiite pilgrims headed to Sayyida Zeinab, killing at least nine people, in an attack claimed by Al-Qaeda affiliate Al-Nusra Front.

An October 2012 attack at the shrine left at least six dead, after a bomb blast in June that year damaged the mausoleum.

In September 2008, before the war broke out, a car bombing near the shrine killed 17 people.

Source: AFP