The Islamic State (Isis) has published a video showing militants destroying ancient artefacts in a Mosul museum with sledgehammer and pickaxes.

IS fighters are seen unveiling old statues in the Ninawa museum dating back to the Assyrian empire and then dragging them down to the ground, where they fall into pieces.

Then, they are depicted pounding 3,000-year-old sculptures with hammers until they are completely shattered. Tens of militants are seen using ladders, hammers and drills to destroy every statue in the museum, including a winged-bull Assyrian protective deity dating back to the 7th century BC.

The winged bulls featured on Iraq currency since the 1950's are gone forever. pic.twitter.com/IOhn8loOdy — Ihsan (@Thawra_city) February 26, 2015

"These ruins that are behind me, they are idols and statues that people in the past used to worship instead of Allah," a bearded IS militant tells the camera, with the immense, partially-demolished winged-bull in the background.

"The so-called Assyrians and Akkadians and others looked to gods for war, agriculture and rain to whom they offered sacrifices," he added, with reference to the ancient civilizations that lived in Mesopotamia for more than 5,000 years in what is now Iraq, eastern Syria and southern Turkey.

"The Prophet Mohammed took down idols with his bare hands when he went into Mecca. We were ordered by our prophet to take down idols and destroy them, and the companions of the prophet did this after this time, when they conquered countries."

"When God orders us to remove and destroy them, it becomes easy for us and we don't care even if they cost millions of dollars," he continues.

A professor at the Archaeology College in Mosul confirmed to the AP that the two sites shown in the video are the city museum and a site known as Nirgal Gate, one of the several gates of the ancient capital of the Assyrian Empire Nineveh.

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"I'm totally shocked," Amir al-Jumaili told the AP. "It's a catastrophe. With the destruction of these artifacts, we can no longer be proud of Mosul's civilization."

The video, dated February 2015 from Mosul and posted on a Twitter account used by IS, comes after Mosul's public library director Ghanim al-Ta'an told The Fiscal Times that IS members burned the city public library, which housed more than 8,000 rare old books and manuscripts.

"IS militants bombed the Mosul Public Library. they used improvised explosive devices," he said.

A history professor at University of Mosul told AP that Islamists began destroying the library earlier this month. Another report said 2,000 books were seen being loaded into pickup tracks.

Mosul is in the centre of 1,791 registered archeological sites, including four capitals of the Assyrian empire - Nineveh, Kalhu, Sur Sharrukin and Ashur.