Iraq's Kurds on Monday released fresh video of freed hostages speaking about torture inside a jihadist-run prison raided last week in a joint Kurdish-US operation.

Elite Kurdish forces supported by US Delta Force fighters freed about 70 people being held by the Islamic State group (IS) near the northern Iraqi city of Hawijah during a raid on Thursday.

The rare operation resulted in the first death of a US serviceman in action in Iraq since 2011.

The government of Iraq's autonomous Kurdish region on Sunday released a video it said was of the raid.

The new footage released on Monday showed several of the freed hostages lining up to shake hands with Kurdish peshmerga fighters in front of a large portrait of the region's leader Massud Barzani, before several spoke about their ordeal.

"Daesh slaughtered my brother who was an officer and handed me his headless body," said a man identified as Saad Farraj, a former policeman, using an Arabic acronym for IS.

Mohamed Hassan Abdallah said he was detained by IS for being a policeman.

"They would put plastic bags on our heads and, when we fell unconscious from suffocation, they would electrocute us," he said.

The freed prisoners said that the jihadists would carry out executions on an almost daily basis inside the prison.

Ahmad Mahmud said he was detained five times by the jihadists, the last of which was three months before the raid.

Torture would last until "you admitted which side you belonged to," he said.

"If you admitted, you were executed, if you didn't, they would carry on torturing you."

IS seized control of large parts of Syria and Iraq last year, declaring a "caliphate", imposing its harsh interpretation of Islam and committing widespread atrocities.

A US-led coalition launched air strikes against the jihadists in August 2014, supporting Iraqi forces, including Kurdish fighters, in attempts to retake lost territory.

Source: AFP