Iraqi forces have opened exit routes for hundreds of civilians to flee the Old City of Mosul as they battle Islamic State militants mounting a last stand in what was the de facto capital of their self-declared caliphate.
US-trained urban warfare units were channelling their onslaught along two perpendicular streets that converge in the heart of the Old City, aiming to isolate the jihadist insurgents in four pockets.
The week-old battle in the Old City is turning into the deadliest of the eight-month US-backed campaign to take back the northern city, which fell to the militants in June 2014.
A Reuters correspondent saw a young girl with facial injuries walking dazed and shocked across the frontline out of heavily-populated district with a group of neighbours. All her family was killed when their house collapsed, they said.
The United Nations voiced alarm on Saturday at the rising death toll among civilians in the fighting, saying as many as 12 were killed and hundreds injured on Friday.
"Fighting is very intense in the Old City and civilians are at extreme, almost unimaginable risk. There are reports that thousands, maybe even tens of thousands, of people are being held as human shields," Lise Grande, the UN humanitarian coordinator in Iraq, said in a statement. "Hundreds of civilians, including children, are being shot."
Iraqi authorities are hoping to declare victory in the northern Iraqi city in the Muslim Eid holiday, which marks the end of the fasting month of Ramadan, during the next few days.
Helicopter gunships were assisting the ground thrust, firing at insurgent emplacements in the Old City.
The government advance was carving out escape corridors for civilians marooned behind Islamic State lines.
There was a steady trickle of fleeing families on Saturday, some with injured and malnourished children. "My baby only had bread and water for the past eight days," one mother said.
More than 100,000 civilians, of whom half are believed to be children, remain trapped in the crumbling houses of the Old City, with little food, water or medical treatment.
Military analysts said Baghdad's campaign to recover Mosul gathered pace after Islamic State blew up the 850-year-old al-Nuri mosque with its famous leaning minaret on Wednesday.
The mosque's destruction, while condemned by Iraqi and UN authorities as another cultural crime by the jihadists, gave troops more freedom to press their onslaught as they no longer had to worry about damaging the ancient site.
It was from the mosque that Islamic State leader Abu Bakr al-Baghdadi announced himself to the world for the first time as the "caliph", or ruler of all Muslims, on July 4, 2014.
Baghdadi fled into the desert expanse extending across Iraq and Syria in the early phase of the Mosul offensive, leaving the fighting there to local IS commanders, according to US and Iraqi officials.
Recent Russian reports that he was killed have not been confirmed by the coalition or Iraqi authorities.