IRBIL, Iraq — The Islamic State group destroyed Mosul’s al-Nuri mosque and its iconic leaning minaret known as al-Hadba when fighters detonated explosives inside the structures Wednesday night, Iraq’s Ministry of Defense said.

The mosque – also known as Mosul’s Great Mosque – is where Islamic State leader Abu Bakr al-Baghdadi declared a so-called Islamic caliphate in 2014 shortly after the city was overrun by the militants and was seen as a key symbolic prize in the fight for Iraq’s second largest city. The minaret that leaned like Italy’s Tower of Pisa stood for more than 840 years.

In a statement posted online after the Ministry of Defense statement, the Islamic State group claimed an airstrike carried out by the United States destroyed the mosque and minaret.

The U.S.-led coalition rejected the claim.

A coalition spokesman, U.S. Army Col. Ryan Dillon, told The Associated Press that coalition aerial surveillance confirmed the mosque was destroyed, but he said a U.S. strike was not the cause.

“We did not conduct strikes in that area at that time,” he said.

Islamic State fighters initially attempted to destroy the minaret in July 2014. The militants said the structure contradicted their fundamentalist interpretation of Islam, but Mosul residents converged on the area and formed a human chain to protect it.