Iraq's government has asked Shia-led militias to prepare to deploy and fight in the Anbar province, after the Islamic State of Iraq and the Levant (ISIL) group overran the provincial capital, Ramadi, Al Jazeera has learnt.

Al Jazeera's Zeina Khodr, reporting from Baghdad, said on Monday that Shia-led militias have been asked by the government to lead a counter-offensive against ISIL in Ramadi.

"They operate under the government-sanctioned Popular Mobilisation Forces and were responsible for pushing ISIL from Diyala and Salahuddin," our correspondent said.

Iraqi special forces soldiers reportedly fled Ramadi on Sunday as ISIL fighters succeeded in breaching their last holdout.

The armed group had earlier made significant gains in its battle to control Ramadi, besieging the army base and killing 15 soldiers in multiple suicide car bomb attacks.

Ramadi had been one of just a few towns and cities to remain under government control in the mainly Sunni province.

Concerns of alienation

There are concerns, however, that involving Shia militias in the fight will alienate some Sunni tribes.

Following the recapture of Tikrit earlier this year, Shia militias were accused of a range of human rights abuses.

Tarik al-Abdullah, secretary-general of the al-Anbar council, a group of provincial tribal leaders, told Al Jazeera on Monday that the Shia militias are "not very welcome".

Abdullah said the government should be supplying weapons and training to volunteer fighters in the province, instead of using militias.

"We need the support of the government. We have a big number of volunteers waiting to participate to liberate our province from [ISIL]," he said.

Meanwhile, the International Office for Migration says 8,000 people have been forced to leave Ramadi, while local officials say that 500 people, including civilians, were killed in the fight for the city in recent days.

The United States downplayed the fall of the city on Monday, with US Secretary of State John Kerry saying he believed ISIL's offensive would be reversed.

"I am convinced that as the forces are redeployed and as the days flow in the weeks ahead that's going to change, as overall [they] have been driven back... I am absolutely confident in the days ahead that will be reversed," Kerry said during a visit to Seoul.