Iraqi forces launch assault on Mosul's Old City

Iraqi forces, backed by worldwide coalition, are fighting to drive out IS militants from the western side of Mosul, locally known as the right bank of Tigris River, but al-Shifaa neighborhood and most of the densely-populated old city center, are still under control of the extremist militants.

"The initial air strikes started at around midnight".

The troops started their push into the old city at 6:00 a.m. local time (0300 GMT) from three directions, Yarallah said, adding that the results of the new push will be announced later.

Machinegun fire crackled and plumes of smoke from missiles rose above the Old City.

Taking back the Old City, a densely populated warren of narrow alleyways, is crucial to recapturing the whole of the former IS bastion.

Iraqi government forces regained eastern Mosul this January, then a month later began the offensive on the western side that includes the Old City.

Up to 150,000 civilians are believed to be trapped in the Old City, where the militants are using them as human shields, United Nations humanitarian coordinator Lise Grande told The Associated Press on Friday.

Iraqi forces have told the BBC that they do not know how many IS militants are holed up inside the Old City.

"These civilians are basically held as human shields in the Old City".

She warned conditions are "desperate", with little food and no clean water.

'They are surrounded by fighting on every side'.

The Old City is home to the centuries-old al-Nuri Mosque, where ISIL leader Abu Bakr al-Baghdadi delivered a Friday sermon in 2014 as his group declared an Islamic caliphate in the areas it controlled in Syria and Iraq.

IS is also under pressure in its last Syrian stronghold, Raqa, where US-backed Kurdish-Arab forces have also been advancing in an offensive to retake the city.