The Iraqi prime minister has said retaking the mosque "marks the end" of the self-proclaimed caliphate
Iraqi forces are said to have retaken one of Mosul's most significant landmarks from Islamic State.
The city's hugely symbolic al-Nuri mosque was recaptured earlier today, officials say.
Mosul has been the major stronghold of IS in Iraq, but efforts to drive the militants from the city have intensified in recent weeks.
In a statement quoted by Reuters, Prime Minister Haider al-Abadi said: "The return of al-Nuri Mosque and al-Hadba minaret to the fold of the nation marks the end of the Daesh [IS] state of falsehood."
It is reported that Iraqi government troops are now continuing to fight militants in small pockets of the city.
Sky News reporter Stuart Ramsay is in the Iraqi city of Erbil, and says the battle for the city is not over just yet.
He explained: "There's still fighting taking place - in fact, we were talking to commanders not long ago... there's a lot of fighting still going on.
"That is likely to go on for about another week or two I would suspect. I don't think it's over yet - but to all extents and purposes Mosul has gone now from Islamic State."
Islamic State still controls significant areas of land in Iraq and Syria.
Efforts are continuing to retake the Syrian city of Raqqa - which had been considered the de facto capital of the self-proclaimed caliphate.
BBC reports that US-backed forces have now 'fully encircled' IS fighters in the city.
A spokesperson for the US military's 'Operation Inherent Resolve' said the US-led coalition "stands ready to support our partners on the ground as they eliminate the last vestiges of ISIS in Iraq and Syria".