MOSUL/ERBIL, Iraq (Reuters) - Iraqi forces are to deploy new tactics in a fresh push against Islamic State in Mosul, military officials said on Friday, after advances slowed in the campaign to drive the militants out of their last stronghold in the country.

Displaced Iraqis flee their homes as Iraqi forces battle with Islamic State militants, in western Mosul, Iraq March 24, 2017. REUTERS/Suhaib Salem

Iraq’s military is assessing opening up another front and isolating Mosul’s Old City, where the militants have put up fierce resistance, a U.S. deputy commanding general for the coalition said.

Families are streaming out of the northern Iraqi city in their thousands each day, headed for cold, crowded camps or to stay with relatives. Hunger and deadly fighting are making life unbearable inside.

The U.S.-backed offensive to drive Islamic State out of Mosul, now in its sixth month, has recaptured most of the city. The entire eastern side and around half of the west is under Iraqi control.

But advances have stuttered in the last two weeks as fighting enters the narrow alleys of the Old City, home to the al-Nuri mosque where Islamic State leader Abu Bakr al-Baghdadi declared a caliphate spanning large areas of Iraq and Syria in 2014.

The militants have used car bombs, snipers and mortar fire to counter the offensive, firing from crowded residential areas and complicating the battle plan especially since troops entered the crowded Old City.

U.S. Army Brigadier General John Richardson, a deputy commanding general in the coalition, said the solution could lie in a change of tactics.

“They (Iraqi forces) are looking at opening another front to force ISIS to fight on two directions and isolate the Old City, so when it is time to go into the old city, potentially they surrender,” he told Reuters.

Richardson said the Iraqi forces could move army units in from the north while other brigades build up positions around the Old City.

“That is going to force ISIS to fight on two fronts, and I don’t think they have that capability,” he said.

Richardson said it was hard to estimate the number of militants left in the city, but said the quality of fighter was declining as their ranks were depleted.

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An Iraqi defense ministry spokesman, who also spoke of new tactics, said elite Counter-Terrorism Service (CTS) forces made some advances against the militants on Friday.

“In the next few days we will surprise Daesh terrorists by targeting and eliminating them using new plans” Brigadier General Yahya Rasool told state TV, without elaborating.

Rasool said CTS forces had advanced in tough, building-to-building battles to recapture areas outside the Old City including al-Yabsat.

Islamic State fighters had been positioning car bombs, and forcing residents to move furniture onto the streets which the militants were booby-trapping to slow Iraqi advances, he said.

Reuters could not independently verify the new advances by the CTS.

No new advances were reported in the Old City, where elite Rapid Response forces, an interior ministry unit, and Federal Police are involved in the fighting. The Federal Police said they were clearing houses and securing areas that they had already entered.

Fighting in the eastern half of the city ended in January, but in a sign of the challenges still faced there, security forces killed one suicide bomber before he detonated his explosives. Police said the bomber had crossed the Tigris from the west.

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Islamic State fighters have stationed themselves in homes belonging to Mosul residents to fire at Iraqi troops, often drawing air or artillery strikes that have killed civilians.

One police officer said the new tactics would also involve deploying additional sniper units against Islamic State sharpshooters. The officer asked not to be identified because of the sensitivity of discussing military tactics.

The militants have launched a series of counter-attacks, sometimes pinning down Iraqi forces on the southern edges of the Old City. Cloud cover and rain in recent weeks have prevented effective air support, military officials say.

As the battle continues, more civilians are being killed or displaced.

Local officials and residents said on Thursday dozens of people were buried in collapsed buildings after an air raid against Islamic State triggered a massive explosion last week.

The U.S. coalition said there was an investigation into those reports.

Outside the city on Friday, hundreds of displaced people trudged through mud clutching suitcases and bags.

One man said that Islamic State snipers were shooting at fleeing residents, and some had been killed in explosions.

Residents described grim living conditions inside the city, saying there was no running water or electricity and no food coming in.

Khaled Khalil, a 36-year-old carpenter whose shop was destroyed in fighting, clutched his three-year-old daughter.

“We’ve been on the move since yesterday. We’re very tired but now we’re safe. Anybody they (Islamic State) catch, they kill. If we have time, we run,” he said.

As many as 600,000 civilians remain in the western half of Mosul.