Iraqi forces battled Islamic State group fighters on Tuesday to push into Mosul's Old City where thousands of civilians remain trapped under jehadist rule.
The city's historic centre is home to the Al-Nuri mosque, where ISIS leader Abu Bakr al-Baghdadi in July 2014 proclaimed an ISIS "caliphate" in jihadist-controlled territory in Iraq and neighbouring Syria.
The forces have recaptured several neighbourhoods from ISIS since starting the push for west Mosul last month, but the battle for the Old City, with its warrens of alleyways, was always expected to be tough.
located on the west bank of the River Tigris which divides the city, the densely populated old centre is difficult for armoured vehicles to navigate and any use of heavy weapons there risks putting civilian lives in danger.
Iraqi forces on Tuesday aimed to press forward to enter the Old City from the Iron Bridge in an area rocked by heavy fighting the previous day, the commander of the Rapid Response Division's 2nd Brigade told AFP.
"The offensive has resumed in the same area as yesterday... Which is made up of large buildings, markets and narrow streets where the enemy is hiding," Brigadier General Mahdi Abbas Abdullah said.
Several buildings have been retaken from the jihadists on the edge of the Old City in the past few days, Iraqi authorities have said.
But the fighting for IS's last major urban stronghold in Iraq puts civilians who remain in the Old City in "terrible danger", an aid coordinator for the United Nations has warned.
"People fleeing are telling us that it's very difficult to enter or leave the Old City," the UN's humanitarian coordinator in Iraq, lise Grande, said in a statement on Sunday.
"Families are at risk of being shot if they leave and they are at risk if they stay," she said.
"It's horrible. Hundreds of thousands of civilians are trapped and they are in terrible danger."