Palmyra: The Islamic State (IS) group has destroyed two ancient Muslim shrines in the Syrian city of Palmyra, the country’s antiquities chief confirmed Wednesday, a day after the ultra hardline jihadists released photos purporting to show the demolition.

The reports were the first of any damage being done by the militants to buildings in Palmyra—a 2,000-year-old UNESCO World Heritage site in central Syria—since they seized control of the city in May.

Maamoun Abdulkarim, the head of the Syrian government’s Antiquities and Museums Department, told The Associated Press that the extremists destroyed the grave of Mohammad Bin Ali, a descendant of Imam Ali, cousin of Islam’s Prophet Mohammed and a deeply revered Shiite saint. The grave was just north of Palmyra.

The second tomb is close to the city’s famed Roman-era archaeological site and was the final resting place of a Sufi scholar, Nizar Abu Bahaa Eddine, who lived in Palmyra some 500 years ago.

On Tuesday, the IS group released before-and-after pictures showing several militants carrying explosives and the shrines reduced to rubble.

Fears for Roman ruins

IS group militants—Sunnis who follow a radical interpretation of Islam that views visiting tombs and religious shrines as tantamount to idol worshipping—have blown up dozens of shrines in territory they control Iraq and Syria.

Since the group captured Palmyra there have been fears that the extremists would destroy the city’s sprawling Roman-era ruins, which were once one of the most popular tourist sites in the Middle East.

Earlier this week, Abdulkarim said he had received ‘unofficial news’ from Palmyra that the militants intended to blow up the town’s main historic site and that he had contacted tribal chiefs in the area to try to dissuade the militants.

The Britain-based Syrian Observatory for Human Rights said it had received information that Islamic State militants have mined the site. The report could not be independently verified.

Syrian authorities say they moved hundreds of priceless artefacts to Damascus ahead of the IS group’s takeover last month, but the fate of those ruins too large to move is now in the hands of the extremists.

Islamic State group militants have already looted and vandalised a museum in the Iraqi city of Mosul and massively damaged the ancient cities of Hatra and Nineveh, both of which are UNESCO World Heritage sites.