Satellite images confirm the destruction of the ancient Nabu temple in Iraq, the UN said late Wednesday, after the Islamic State group claimed to have blown it up.

The UN training and research agency UNITAR said it had analysed satellite images collected on June 3 over the ancient Assyrian city of Nimrud in northern Iraq.

"Compared to imagery collected 12 January 2016, we observe extensive damage to the main entrance of what is known as Nabu Temple," the agency said, providing the two sets of satellite images.

In its latest attack on a historic site under its control, IS released a video this week claiming to have blown up the 2,800-year-old temple, devoted to the Babylonian god of wisdom.

The video showed shots of an information sign at the temple followed by a massive explosion. One of the jihadists in the film also threatened to blow up the Egyptian pyramids and the Sphinx.

Nimrud, one of the jewels of the Assyrian era, was founded in the 13th century BC and lies on the Tigris River around 30 kilometres (18 miles) southeast of Mosul, Iraq's second city and the IS group's main hub in the country.

UNITAR said Nimrud was "included in Iraq's Tentative List of sites which are likely to be nominated for inscription on UNESCO's World Heritage List".

It remained unclear when the ancient temple had been destroyed.

The IS footage also showed bulldozers destroying the Mashki and Nergal gates at Nineveh, near Mosul.

But Christopher Jones, an expert on Neo-Assyrian Empire who runs an archeology blog, pointed out that the jihadist group had already previously released a photo essay showing the destruction of the Mashki gate, which he said had been bulldozed on April 10.

As for the Nergal gate, he said IS fighters had already chisled the face off an imposing granite Assyrian winged bull representing a lamassu, or an Assyrian protective deity, flanking the gate back in February.

"This suggests that ISIS has gone back to re-destroy artifacts that it already destroyed once, in order to get footage for new videos," he wrote on his blog Wednesday.

In the IS jihadists' extreme interpretation of Islam, statues, idols and shrines amount to recognising objects of worship other than God and must be destroyed.

The militants have systematically destroyed heritage sites in areas they control, including much of Syria's ancient city of Palmyra before they were chased out by Syrian regime troops in March.