Daesh militants on Wednesday blew up the Grand al-Nuri Mosque of Mosul and its famous leaning minaret, Iraq's military said in a statement.

Three years ago, Daesh leader Abu Bakr al-Baghdadi stood at this mosque and declared a "caliphate" spanning parts of Syria and Iraq.

In response to Wednesday’s action, Iraqi Prime Minister said: ''Blowing up the al-Hadba minaret and the al-Nuri mosque amounts to an official acknowledgement of defeat.''

The Iraqis called the 45-metre leaning minaret Al-Hadba, or "the hunchback," reported Reuters.

However, Daesh’s Amaq news agency accused U.S Forces of destroying the mosque, a claim swiftly denied by the U.S.-led coalition fighting the militant group.

"We did not strike in that area," coalition spokesman U.S Air Force Colonel John Dorrian told Reuters by telephone.

"The responsibility of this devastation is laid firmly at the doorstep of ISIS (Daesh)," U.S Army Major General Joseph Martin, commander of the coalition's ground component, said in a statement.

The media office for Iraq's military distributed a picture taken from the air that appeared to show the mosque and minaret largely flattened and reduced to rubble among the small houses of the Old City, the historic district where the militants are under siege.

A video seen on social media showed the minaret collapsing vertically in a belch of sand and dust, as a woman lamented in the background, "The minaret, the minaret, the minaret,"Reuters reported.