An estimated 400,000 Iraqi civilians are trapped in Mosul's Old City in north Iraq as fighting intensifies and people continue to flee, the UN refugee agency representative warned on Friday.

"The worst is yet to come," said Bruno Geddo, the representative of the UN Refugee Agency (UNHCR) in Iraq.

Speaking by phone with the UN News Center, Geddo said the fighting in the west has been more intense than in the less densely populated east of the city, where the battle ended in January.

"People are stuck between a rock and a hard place," he said. "There's fighting shelling, bombing."

When people try to flee, extremists shoot them. Some have tried to leave during prayers or under cover of fog at first light, but were killed, Geddo said.

Meanwhile, life in the Old City is becoming impossible with a lack of food, clean water or fuel, Geddo said.

Meeting with civilians at the UNHCR transit and reception centre at Hammam al-Alil, outside of the city centre, Geddo said the number of people moving through has "surged' in recent days with up to 12,000 people arriving daily.

Some 340,000 people have been displaced since the fighting in Mosul started last October. Of those, about 72,000 have returned home.

The UN representative called on all those fighting to allow civilians to leave areas of conflict for safer zones, and no one should be forced to come back home.

"Liberating Mosul is necessary but not sufficient," Geddo said. "We equally have to get it right with the protection of civilians and in the humanitarian response."

Mosul witnessed a fighting between the Iraqi government forces and Islamic State (IS/Da'esh) terrorists

The Iraqi government force's advance toward Mosul came after the Iraqi Prime Minister Haider al-Abadi announced on Feb. 19 the start of an offensive to drive the extremist militants out of the western side of Mosul, locally known as the right bank of Tigris River which bisects the city.

Late in January, Abadi declared the liberation of the eastern side of Mosul, or the left bank of Tigris, after more than 100 days of fighting against the Islamic State (IS) militants.

However, the western side of Mosul, with its narrow streets and a heavy population of between 750,000 and 800,000, appears to be a bigger challenge to the Iraqi forces, according to the United Nations estimates.

Mosul, 400 kilomters north of the Iraqi capital of Baghdad, has been under IS control since June 2014, when Iraqi government forces abandoned their weapons and fled, enabling IS militants to take control of parts of Iraq's northern and western regions.

source: Xinhua