QAYYARAH:  Tens of thousands of Iraqi forces were making gains from the Islamic State group in Mosul Tuesday in an offensive US President Barack Obama warned would be a “difficult fight”.

With the crucial battle in its second day, Iraqi commanders said progress was being made as fighters pushed on two main fronts against the jihadists’ last stronghold in Iraq.

The US military, which is leading a coalition providing air and ground support, said Iraqi forces even looked “ahead of schedule” but senior Western officials warned the battle would take time.

“Mosul will be a difficult fight. There will be advances and there will be setbacks,” Obama said, as the Pentagon warned IS was barring civilians from fleeing the city and using them as human shields.

“This will be, I think, a key milestone in what I committed to doing when ISIL first emerged,” Obama said, using an acronym for the jihadist group, adding the Mosul operation was “another step toward their ultimate destruction”.

Advancing in armoured convoys across the dusty plains surrounding Mosul, forces moved into villages defended by pockets of IS fighters after intensive aerial bombardment.

Some families cautiously approached security forces waving white flags while others remained in their homes, in line with the instructions contained in leaflets Iraqi aviation rained on the area in recent days.

In one village south of Mosul, part of the Al-Shura district, the men were promptly isolated and herded into a handful of buildings for screening.

“Our forces are checking profiles against information we have from local sources because we are trying to find IS members,” a federal police major said.

Most of the men wore long beards because the IS members who ruled them for more than two years banned trimming them.

Abu Abdullah, a villager, asked one of the police fighters for a cigarette, also prohibited by the extremist jihadist organisation.

– ‘Empty streets’ –

On the eastern front, Iraqi forces entered Qaraqosh, which jihadists captured in August 2014 and was once the biggest Christian town in Iraq.

The town was still to be fully retaken but displaced Christians in the Kurdish capital of Arbil held prayers and then celebrated outside a church late Tuesday.

“We have been through a lot of suffering and today we are looking forward to returning to our region as soon as possible,” said Hazem Djedjou Cardomi, as a crowd of hundreds around him danced and sang.

The long-awaited Mosul offensive was launched on Monday, with some 30,000 federal forces leading Iraq’s largest military operation since the 2011 pullout of US troops.

Retaking Mosul would deprive IS of its last major Iraqi city, dealing a fatal blow to the “caliphate” the jihadists declared two years ago after seizing large parts of Iraq and neighbouring Syria.

Iraqi commanders said the jihadists were hitting back with suicide car bomb attacks but that the offensive was going as planned.