Extremists from the group calling itself Islamic State have severely damaged a 10th-century monastery in Mosul as the group continues its swathe of dismantling any piece of cultural heritage it can.

The Catholic Fides news agency reported that the ancient monastery of St. George, known as Mar Gorgis, has sustained significant damage to its façade, contrary to earlier reports that the church had been destroyed.

The façade had purportedly been blown up to remove the symbol of Christianity in the structure, the cross, which IS have been systematically removing in different places of worship in Iraq since its reign of terror began last year.

"IS destroyed the front wall of St. George monastery to remove the big built-in cross," Archimandrite Emanuel Youkhana, a member of the Assyrian Church of the East who runs a humanitarian aid in northern Iraq, told Aleteia news agency.

In December, IS removed the crosses that stood on the dome and the roof of the monastery in its quest to remove symbols and vestiges of Christianity in the area.

A cemetery adjacent to the church, where many Iraqi Christian soldiers killed in the Iraq-Iran war were buried, was also destroyed.

Fides was told by local Iraqi people the monastery served as a detention center operated by IS.

The monastery is believed to have held at least 150 detainees, including Sunni opponents, who had been kept previously in a prison in Badush.

It was also rumored that groups of women had been brought to the monastery.

In an interview with Aleteia news agency, Eastern Christianity expert Erica Hunter explained that the extremists seemed bent upon destroying important cultural landmarks in Iraq.

"[IS extremists] have destroyed mosques, tombs and other medieval sites, as well as the recent destruction of Nimrud, so regrettably I see the medieval churches of Mosul as being 'on their list' of cultural destruction, which of course undermines the morale of the local inhabitants," said Hunter, a senior lecturer in Eastern Christianity at the University of London.