IS 'blow up' iconic mosque where caliphate was declared

The Grand al-Nuri Mosque, including the minaret that had flown the IS black flag, was reduced to rubble.

Islamic State militants have blown up the iconic mosque in Mosul where their leader once declared the self-styled Islamic caliphate, the Iraqi military have said.

Abu Bakr al-Baghdadi proclaimed himself "caliph", or ruler of all Muslims, from the pulpit of the medieval Iraqi mosque three years ago after so-called IS overran parts of the country and neighbouring Syria.

Islamic State's Amaq news agency accused American aircraft of destroying the Grand al-Nuri Mosque.

Abu Bakr al-Baghdadi delivered a sermon at the mosque during his first public appearance in 2014. AP

But the Iraqi military said the explosion happened as their elite units got to within 50 metres of the mosque as they battled through Mosul's Old City.

"The (Islamic State) terror gangs committed another historical crime by blowing up the al-Nuri mosque and its historical al-Hadba minaret," it said in a statement.

The group's black flag had flown from the building's leaning minaret since June 2014.

Iraqi officials had hoped the mosque could be recaptured in time for Eid al-Fitr. AP

Iraqi officials had hoped the mosque could be recaptured in time for Eid al-Fitr, the festival heralding the end of the Muslim fasting month of Ramadan.

The first day of the Eid falls this year on June 25 or 26 in Iraq.

In January Islamic State militants destroyed famous ancient monuments in Palymra, including the Tetrapylon monument and a Roman theatre, a month after retaking the Syrian city.

The Syrian military announced the recapturing of Palmyra in March.