Islamic State militants have allegedly burned 45 people to death in an Iraqi town, the BBC reports.

The police chief of al-Baghdadi in the western region of the country said that he didn't know who those killed were, or why they were subjected to such brutal treatment, but he believed them to be members of the security forces.

Col Qasim al-Obeidi added that the compound where security personnel and local officials live is now under attack from militants, and urged the international community to step in.

Islamic State had besieged al-Baghdadi in Iraq's Anbar province since October, and it was finally captured by the jihadists last Thursday. Hundreds of IS militants swarmed the town from two directions, and though government forces managed to retake several buildings on Friday, they withdrew the following day, handing the town back over to IS.

According to Reuters, a local Iraqi official confirmed that "Ninety per cent of al-Baghdadi district has fallen under the control of the insurgents."

Of some concern is that the Ayn al-Asad air base, where US Marines are training Iraqi troops, is just five miles outside the town.

Several suicide bombers attacked the base on Friday, though the Pentagon said that most of the IS militants were killed either by detonating their suicide vests or by Iraqi government troops.

The BBC says that poor communication on the ground in Iraq means it is difficult to confirm the latest report of IS brutality in al-Baghdadi. However, the group released a video earlier this month showing captured Jordanian pilot Mouath al-Kasaesbeh being burnt alive in a cage.

President Obama later condemned the terrorist faction of "betraying" Islam by carrying out such barbaric acts. Muslim clerics across the world have also expressed "deep anger" over Kasaesbeh's murder.