Islamic State (IS) militants have destroyed ancient remains of the 2,000-year-old city of Hatra in northern Iraq, the tourism and antiquities ministry says.

An official said the ministry had received reports from its employees in the northern city of Mosul, which is under the control of the radical Islamist group, that the site at Hatra had been demolished on Saturday.

It was difficult to confirm the reports and the ministry had not received any pictures showing the extent of the damage, the official said.

But a resident in the area said he heard a powerful explosion early on Saturday and said other people nearby had reported that IS militants had destroyed some of the larger buildings in Hatra and were bulldozing other parts.

Hatra lies about 110 kilometres south of Mosul, the largest city under the IS group's control.

Director general of the United Nations cultural body UNESCO, Irina Bokova, condemned the reported wanton destruction of the ancient city.

"The destruction of Hatra marks a turning point in the appalling strategy of cultural cleansing underway in Iraq," UNESCOsaid.

"Official sources today reported the destruction of the World Heritage property of Hatra.

"This is a direct attack against the history of Islamic Arab cities, and it confirms the role of destruction of heritage in the propaganda of extremists groups."

However Mohammed Nuri, an MP from southern Nineveh province, where Hatra is located, cast doubt on whether the reports were accurate, saying "until this moment, there are no confirmed reports that Hatra has been destroyed".

"Hatra is somewhat isolated, and residents are not nearby," he said.

"I have not heard of someone who physically saw the destruction taking place."

A week ago the militants released a video showing them smashing statues and carvings in Mosul's museum, home to priceless Assyrian and Hellenistic artefacts dating back 3,000 years.

On Thursday they attacked the remains of the Assyrian city of Nimrud, south of Mosul, with bulldozers.

UNESCO said the destruction amounted to war crimes.

Hatra dates back 2,000 years to the Seleucid empire which controlled a large part of the ancient world conquered by Alexander the Great.

It is famous for its striking pillared temple at the centre of a sprawling archaeological site.

Reuters