Abu Saif, a 47-year-old former company manager contacted by AFP, said the streets felt eery as fighters and civilians alike stayed indoors.

"The atmosphere in Mosul is strange, the sky is constantly black with smoke from tyres Daesh (IS) lit everywhere," he said on Tuesday.

"There is also the black smoke from the burning oil in the trenches Daesh dug around the city to hide their members' movements.

"The streets are empty, the people have been staying at home since the strikes started yesterday," said Abu Saif, a resident of the eastern half of Mosul.

He said he could hear air strikes and explosions coming from Bartalla, a Christian town just east of Mosul on which Kurdish and federal forces are advancing.

"It seems a lot of Daesh members have already left this side of the city and crossed to the other bank of the river," Abu Saif said.

Military sources have predicted that east Mosul could be significantly easier to retake than the western half, which is considered the jihadists' real bastion in the city.

"They still have a lot of snipers perched in high places around here though and we know they have lots of car bombs ready and have planted roadside bombs everywhere," he said.

Abu Saif, who is now jobless and managed to smuggle his family out of the city earlier this year, said the people around him were torn between the prospect of being freed from the jihadists' yoke soon and the fear that they will not survive the impending battle.

"There is this happiness inside us besieged people of Mosul, because we feel that we are about to be rescued," he said.

"But we are scared that Daesh can still carry out acts of revenge against the population."

As the noose has tightened around Mosul in recent months, IS fighters have executed countless people, including their own, over accusations of spying or collaborating with government forces.

Abu Saif said two people were executed near Al-Zuhoor school as recently as Sunday.

"There is also the fear of all these bombs falling from the sky. People have moved back into the old shelters that were used during the war with Iran in the 80s," he said.

"Many are also living in their basements, especially in the old part of the city where houses have cellars."

Abu Saif said that some families were moving in together to share a single home, in an attempt to feel safer and make better use of dwindling food and electricity supplies.

“People are also locking up their belongings, fearing that Daesh could steal them as they flee and also that riots and looting could break out after the liberation," the father of three said.

Iraqi forces have some way to go before reaching the city proper and senior commanders have warned that the Mosul battle could last weeks or more. (AFP)