UNESCO Director General Irina Bokova has condemned the destruction by ISIS of the ancient Assyrian archaeological site of Nimrud in Iraq, describing the act as a war crime.

Bokova was speaking in response to the reports that have today been confirmed by the Iraqi government, that Nimrud had been attacked the day before by “armed extremists using bulldozers”. An Iraqi antiquities official speaking to AP said that the attack started after noon prayers, and that some of the trucks may also have been used to haul away artifacts.

The 13th century in northern Iraq site is considered one of the most important remnants of Assyria, an ancient kingdom that began in about 900 BC. In 1988, a collection of 613 gold jewels, ornaments and precious stones were unearthed from a royal tombs found there in what has been described as one of the greatest archaeological finds of the 20th century.

There have been fears that Islamic State would target Nimrud, after it used drills and sledgehammers to vandalise museums and antiquities in Mosul and Nineveh last week. It is widely believed that these destructive acts are part of the extremist group’s campaign to enforce its violent interpretation of Islamic law, and to destroy ancient archaeological sites that they say are against religion.

In a statement released today, Bokova stated: “We cannot remain silent. The deliberate destruction of cultural heritage constitutes a war crime. I call on all political and religious leaders in the region to stand up and remind everyone that there is absolutely no political or religious justification for the destruction of humanity’s cultural heritage.”