Islamic State (Isis) fighters fleeing the Iraqi Army's advance into Fallujah have been captured in their hundreds, pro-government forces have claimed, as they pose as refugees to get out of the city. This follows the mass fleeing of the city's residents.

As US-backed Iraqi forces continue their bloody assault into the Iraqi city, which has been held by the IS for two years, the Pentagon has said US Apaché helicopters had hit Isis targets in Fallujah. It is the first time the helicopters have been deployed in Iraq since the US invasion.

"We have arrested 546 suspected terrorists, who had fled by taking advantage of the movements of displaced families over the past two weeks," Hadi Rzayej, the police chief for Anbar province told the French news agency AFP.

Iraqi forces have been screening men and teenage boys leaving Fallujah and crossing their lines. Interrogations can take up to several hours.

Since the start of the Iraqi government's offensive in Fallujah, which began in May, some 27,600 residents have fled the city that has been Isis's largest stronghold in the west of the country. Around 7,000 of them were able to flee after Iraqi government forces retook a key road into the city on 12 June

The numbers of residents fleeing via the corridor and Al-Salam intersection to the southwest of the city appeared to slow up on Monday 13 June, the Norwegian Refugee Council's has reported. Remaining civilians in the city are believed to have been left trapped in northern districts, according to the aid agency.

Iraqi forces fighting their way into Fallujah have made slow progress in the city and have faced devastating Islamic State counter attacks that have involved suicide bomb assaults and the deployment of snipers around the city.

Fighting ISIS
An Iraqi Shi'ite fighter fires a rocket-propelled grenade (RPG) during clashes with Islamic State militants on the outskirt of Fallujah, IraqReuters

"This is a phase of street battles now, our fighters and the militants are sometimes only 20 metres from each other, fighting with light weapons," said Abdelwahab al-Saadi, the overall commander of the Iraqi operation.

A litany of atrocities – perpetrated by both sides – have emerged since Iraqi forces, supported by Shia militias, began their bloody advance into the city.

Aid agencies have warned that Fallujah residents, some of them children, risk being forced to fight for Isis as the militant group uses food to lure the starving civilians to enlist.

Residents from the city have drowned or been killed by Daesh (Isis) snipers as they attempted to leave Fallujah across the Euphrates. Footage has emerged of the inhabitants using improvised rafts in attempts to leave the embattled city. They were reported to have used refrigerators and cupboards to cross the river rather than face the IEDs left on other roads by Islamic State.

At the same time, civilians caught up in the advance by Iraqi Army and so-called Popular Mobilisation Forces risk torture at the hands of pro-government Shia militia.

According to Yahya al-Muhamadi, an Anbar council member working with displaced civilians and quoted by the Associated Press, five of those detained died while in the group's custody.

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