An American special forces operator has been killed in a joint raid on an Islamic State prison in northern Iraq, a US defense official has said.

It marks the first US servicemen killed in ground combat against the extremist group.

Details remain sketchy on the early morning raid in Hawija, but US media reports indicated at least 70 hostages were freed and about 10 IS militants were killed.

Another five militants were reportedly detained.

A Pentagon spokesman told Reuters the operation was launched "after receiving information that the hostages faced imminent mass execution".

A senior US defence source told Fox News most of the freed prisoners were Iraqi security forces.

"People were chained to walls," the official said.

The New York Times first reported the raid, citing Iraqi officials.

The mission was conducted alongside Kurdish commandos and utilised airstrikes to cut off roads leading to the prison, the Times reported.

Iraqi forces and the US-led coalition have been ramping up the fight against IS in the region.

Hawija, which is under IS control, has been a vital flash point to operations in recent weeks, the Times reported.

IS has been the target of daily airstrikes in Iraq and Syria by a US-led coalition for more than a year.