Militants from Islamic State have burned 45 people to death in the western Iraqi town of al-Baghdadi, according to the local police chief.

Col Qasim al-Obeidi said the motive was unknown but he believed some of the victims were members of the security forces.

He has pleaded for help from the government and international community and said the compound, which houses the families of security personnel and local officials, was now under attack.

It follows the capture of al-Baghdadi, near Ain al-Asad air base, by ISIS fighters last week.

Captured: The western Iraqi town of al-Baghdadi where a local police chief says 45 people have been burned to death in the latest brutal attack by ISIS

The unconfirmed reports have haunting similarities to the video published earlier this month, showing militants burning alive a Jordanian air force pilot, whose plane crashed in Syria in December.

Al-Baghdadi had been besieged for months by Islamic State fighters before its fall. It had been one of the few towns to still be controlled by the Iraqi government in Anbar province, where IS and allied Sunni Arab tribesmen launched an offensive in January 2014.

On Friday, Pentagon spokesman Rear Adm John Kirby, played down its capture, telling reporters it was the first time in the last couple of months that the jihadist group had taken new ground.

But with 320 US Marines stationed just five miles away at the Ain al-Asad air base, training members of the Iraqi army's 7th Division, it will cause concern.

The base was attacked by several suicide bombers, on Friday with the militant repelled by Iraqi troops backed by US-led coalition aircraft.

Horrific: The latest claims have haunting similarities to Jordanian pilot Moaz al-Kasasbeh, who was burned to death in a cage (pictured) in a brutal execution filmed by the jihadists

Kashmiri demonstrators hold up a flag of the Islamic State of Iraq and the Levant (ISIL) during a demonstration against Israeli military operations in Gaza

In a separate development on Tuesday, the influential Shia cleric Moqtada Sadr announced he was withdrawing his forces from an umbrella group of Shia militia fighting IS alongside the Iraqi army.

He cited what he called the bad behaviour of other militia within the Popular Mobilisation Forces, whom he accused of 'wreaking havoc through murdering, kidnapping and violating sanctuaries'.

Shia militia have been accused of kidnapping and killing scores of Sunni civilians since Islamic State launched an offensive in northern Iraq last June that saw it seize large swathes of the country.

Elsewhere, there are reports at least 35 more Egyptian Christians are feared to have been kidnapped by jihadists in retaliation for air strikes on targets in Libya.

Militants from the Islamic State and Ansar Al-Sharia are understood to have rounded up dozens of farm workers in the wake of bombings by Cairo, it was reported by local media.