Followers of the Shia cleric Muqtada al-Sadr have gathered in the Iraqi city of Samarra, home to the Askari shrine, one of the most venerated sites for Shia Muslims.

Footage shot by a freelance cameraman in and around the city on Tuesday showed truckloads of volunteers, who have joined an armed group known as the al-Salam brigade, in order to protect the holy site.

They intend to defend the Askari shrine from Sunni rebels led by the Islamic State group who have captured large swathes of territory in northern Iraq in recent weeks.

In 2006 the shrine, 95km north of the capital, Baghdad, was severely damaged in an attack attributed to al-Qaeda.

In June this year the shrine came under threat again when Islamic State group fighters took over several neighbourhoods of Samarra before being expelled by the Iraqi army.

The Askari shrine contains the tombs of the 10th and 11th imams - Ali al-Hadi, who died in 868, and his son Hassan al-Askari, who died in 874. Both are descendants of the Prophet Muhammad, and believed by Shias to be among his successors.

Some of the volunteers, including brigade commander Kadhim al-Isawi, paid their respects at the shrine on Tuesday.

Source: Al Jazeera and agencies