US and Iraqi forces freed around 70 hostages held captive by the Islamic State in northern Iraq after learning that they faced "imminent mass execution".

The operation saw the first US soldier killed in combat in the country since the US began its counter-IS military campaign in August 2014, officials said.

The raiders killed and captured a number of militants and recovered what the Pentagon called a trove of valuable intelligence about the terrorist organisation.

The US service member who died was not publicly identified pending notification of relatives.

In a written statement, Pentagon press secretary Peter Cook said the operation was undertaken near the town of Hawija at the request of the Kurdish Regional Government, the semi-autonomous body that governs the Kurdish region of northern Iraq. He said US special operations forces supported what he called an Iraqi peshmerga rescue operation.

The peshmerga are the Kurdish region's organised militia.

The circumstances in which one US military member was killed were unclear, but one US official said the American had been shot in a firefight at the scene. Mr Cook said the service member was wounded during the mission and died after receiving medical care. He said four Peshmerga soldiers were wounded.

Another US defence official said the US role in the rescue mission was mainly limited to four areas: transporting Iraqi soldiers to the scene in five US special operations helicopters; providing airstrikes before and after the mission; advising Kurdish fighters and Iraqi security forces; and providing the Iraqis with intelligence for the operation.

US combat troops have rarely, if ever, participated directly in combat against IS fighters on the ground since the US mission began in 2014. The US has mostly limited its role to training and advising Iraqi and Kurdish forces and providing daily airstrikes in IS-held areas of Iraq.

The US defence official said the number of IS members killed was not to be made public immediately but that it was more than 10.

Mr Cook said that of the approximately 70 prisoners freed, more than 20 were members of the Iraqi security forces. He did not say who the others were.

Mr Cook said five IS members were detained and "a number" were killed.

"In addition, the US recovered important intelligence" about IS, Mr Cook said.

The relative of one of the Kurdish hostages said he had been informed of their rescue in a US-led raid.

Irfan Sadradeen, the uncle of Kurdish peshmerga fighter Meriwan Mawlud, said he was contacted by a peshmerga official who informed him about the raid on the Islamic State group near Hawija. He said he was told that paratroopers landed at a poultry farm, close to the home of the main sharia judge of Hawija, where they launched their rescue.

"We are waiting for more information. A peshmerga official called us today confirming the news of the raid," he said, adding that he was told 15 IS fighters were killed in the raid. "None of them arrived to this area yet but we are waiting for them," he added.

Tariq Rafiq, the father of a peshmerga soldier, said he was told by Kurdish authorities that the rescue mission happened at 2am local time and that the prisoners were being held in a judge's house in Hawija.

"We are now together with other family members waiting for more information," he said.