A video allegedly showing ISIS militants destroying a historic city in northern Iraq dating back to the 13th century B.C. using sledgehammers, drills and barrel bombs, has emerged this morning. ISIS fighters can be seen hammering and drilling away at sculptures and stone slabs believed to be some 3,000 years old in the ruins of the ancient Assyrian city of Nimrud, located near the Islamic State-controlled city of Mosul. The seven-minute expertly edited video, purportedly shows Islamic State destroying the relics before bulldozing and blowing up the ruins, completely obliterating the historic site. The destruction at Nimrud, which took place last month, follows other attacks on cultural heritage sites carried out by the Islamic State, which now holds a third of Iraq and neighboring Syria in its self-declared caliphate. Scroll down for video . Attack: An ISIS militant uses a sledgehammer to destroy a several thousand years old stone slab in a video allegedly showing the group's attack on the ancient ruins of the city of Nimrud, near Mosul, Iraq . As well as attacking the city by hand, hammer and drill, the video shows the group making barrel bombs which they lined up along the ancient relics inside the ruins of what was once the capital of the Assyrian Empire, founded some time in the 13th century B.C. ISIS released the video, believed to have been filmed last month, showing militants smashing artifacts in the historic city, which is on UNESCO's tentative list of world heritage sites, before blowing it up . The attack on the ancient site horrified archaeologists when it was first reported last month, and has been declared a 'war crime' by U.N. Secretary-General Ban Ki-moon. The seven-minute video, posted late Saturday, shows bearded militants using sledgehammers, jackhammers and saws to take down huge alabaster reliefs depicting Assyrian kings and deities. A bulldozer brings down walls, while militants fill barrels with explosives and later destroy three separate areas of the site in massive explosions. 'God has honored us in the Islamic State to remove all of these idols and statutes worshipped instead of Allah in the past days,' one militant says in the video. Another militant vows that 'whenever we seize a piece of land, we will remove signs of idolatry and spread monotheism.' Attack: The video, made available by a Jihadist media outlet, shows ISIS militants destroying a stoneslab with a sledgehammer at what they say is the ancient Assyrian city of Nimrud in northern Iraq . Horrified: The attack on the ancient site has been declared a 'war crime' by U.N. Secretary-General Ban Ki-moon . Islamic State militants have been destroying ancient relics on several sites, daying they promote idolatry that violate their fundamentalist interpretation of Islamic law . It is believed parts of the footage may be from a nearby site as some of the figures in the Nimrud video appears to have rebar, ribbed steel bars designed to reinforce concrete that are a technique of modern building. However, an Iraqi Antiquities Ministry official, speaking on condition of anonymity, said all the items at Nimrud were authentic. When the destruction was first reported several weeks ago a Mosul tribal leader confirmed that SIIS had 'looted the valuables in Nimrud and then proceeded to level the site to the ground. There used to be statues and walls as well as a castle that Islamic State has destroyed completely.' 'In a new crime in their series of reckless offenses they assaulted the ancient city of Nimrud and bulldozed it with heavy machinery, appropriating archaeological attractions dating back 13 centuries BC,' the United Nations cultural agency UNESCO said in a statement last month. UNESCO head Irina Bokova added: 'This is yet another attack against the Iraqi people, reminding us that nothing is safe from the cultural cleansing under way in the country: it targets human lives, minorities, and is marked by the systematic destruction of humanity's ancient heritage,' she said . Complete destruction: The end of the video allegedly shows Islamic State militants blowing up the ancient ruins near Mosul . One of many: This is only the most recent video purporting to show Islamic State fighters destroying invaluable heritage sites . Islamic State militants have been destroying ancient relics on several sites, saying they promote idolatry that violate their fundamentalist interpretation of Islamic law, including the ancient Iraqi city of Hatra, a UNESCO World Heritage site. Authorities also believe they've sold others on the black market to fund their atrocities. This is only the most recent proof of Islamic State fighters destroying invaluable heritage sites. A shocking video emerged last week, showing ISIS militants using sledgehammers and AK-47 rifles to destroy walls and statues in Iraq's UNESCO World Heritage city of Hatra. In the slickly produced seven minute footage, jihadists are shown smashing shrines and statues in the 2,000-year old city. Militants are also recorded chipping away at the bases of some of the larger wall sculptures and cracking boulders into ancient city pillars, while eerie music plays in the background. The video cuts to jihadists speaking directly to the camera with one declaring they destroyed the site because it is 'worshipped instead of God'. Last month, ISIS terrorists were pictured toppling crosses, smashing Christian relics with hammers and erecting the black flag of ISIS on churches in Nineveh, the ancient capital of the Assyrian empire. The Assyrians first rose around 2,500 B.C. and at one point ruled over a realm stretching from the Mediterranean coast to what is present-day Iran. They left dozens of palaces and temples decorated with huge reliefs mainly depicting their kings' military campaigns and conquests, hunting lions and making sacrifices to the gods. Their main hallmark was the colossal winged man-headed lions or bulls, protective deities put at the entrances of palaces and temples weighing about 10-30 tons each, some of which are now at the British Museum. Located on the eastern side of the Tigris River, Nimrud was founded in the 13th century B.C. During the reign of King Ashurnasirpal II, Nimrud served as the second capital for Assyrian Empire. Other Assyrian capitals were Ashur, Dur Sharrukin and Ninevah. Nimrud and some of its kings were mentioned in the Bible, the city mentioned under the name of Calah or Kalhu in the Book of Genesis. Excavations at Nimrud were first started by the British traveler and archaeologist Austen Henry Layard from 1845 to 1851, followed by other foreign and local excavation missions. The city is surrounded by a four-side wall measuring 8 kilometers (5 miles) long. Among the ruins are the grand palace of Ashurnasirpal II, as well as the temples of Nabu, the god of writing and the arts, and other temples. Among the most significant discoveries at Nimrud were four tombs of royal women. There, a collection of 613 pieces of gold jewelry and precious stones were unearthed. They survived the looting of the Iraqi National Museum that followed the U.S.-led invasion in 2003 as they were kept in a vault at the Central Bank of Iraq building by Saddam Hussein's government.
ISIS fighters destroyed ancient ruins of Iraqi Assyrian city of Nimrud dating back to the 13th century B.C.
The attack, near Mosul, took place last month, but a seven-minute video of destruction has now emerged .
It shows militants hacking and drilling away at 3,000-year-old relics and blowing up the ancient ruins .
The U.N. Secretary-General Ban Ki-moon has called the destruction of the Nimrud ruins 'a war crime'