ISIS thugs have burned 12 people alive including a family of four after accusing them of trying to flee from an Iraqi city they control.

Extremists forced the civilians into cages and doused them with oil before setting them alight in the city of Hawija in Kirkuk Province, northern Iraq.

The victims were accused of trying to escape to nearby Kirkuk city, which is under government control.

ISIS thugs have burned 12 people alive including a family of four after accusing them of trying to flee from an Iraqi city they control (file picture)

A source told al-Sumeiryeh news that ISIS, on the retreat in Iraq, caught the civilians as they made their way towards the al-Elm region.

Their hands were tied and they were led to metal cages before fanatics poured oil on the prisoners and set them alight, the 'well-placed' source claimed.

The gruesome execution comes after it emerged that an ISIS preacher and leader was executed by the militants after he accidentally suggested that the group's leader had died.

Senior ISIS leader and preacher, Abu Qutaiba was burned to death in the group's stronghold town of Tal Afar, according to a source quoted on Alsumaria News, an independent Iraqi satellite TV network.

The gruesome execution comes after it emerged that an ISIS preacherr was executed by the militants after he accidentally suggested that the group's leader Abu Bakr al-Baghdadi (pictured) had died

He had been arrested over charges of 'stirring sedition' through a Friday prayer sermon in which he inadvertently suggested the group's runaway leader, Abu Bakr al-Baghdadi had possibly died during an emotional sermon.

The group had previously ordered a punishment of 50 lashes for anyone who mentioned Baghdadi's survival or otherwise, a source told the local TV network.

The source said that the move came to avert a possible escalation of simmering leadership conflicts within the group.