Hostages at risk of “imminent mass execution” have reportedly been rescued in Iraq during a high-risk joint mission by US and Kurdish troops, which left one US soldier dead.

Residents in Hawijah, Iraq reported seeing Chinook helicopters and air strikes during the early morning raid in an IS prison compound in the area, which reportedly rescued 70 hostages, including more than 20 Iraqi soldiers, according to the Pentagon.

“This operation was deliberately planned and launched after receiving information that the hostages faced imminent mass execution,” Pentagon press secretary Peter Cook said in a statement.

• Islamic State boss ‘hit’
• Swordsman kills teacher in Sweden
• Islamic State blamed for massive terror attack

One of the Americans was wounded “acting in support of Iraqi peshmerga forces after they came under fire from ISIL,” and subsequently died after receiving medical attention, Mr Cook said.

General Lloyd Austin, the commander of all US forces in the Middle East, described the rescue operation as “complex and highly successful.”

“We commend and congratulate the brave individuals who participated in this successful operation that saved many lives, and we deeply mourn the loss of one of our own who died while supporting his Iraqi comrades engaged in a tough fight,” he said.

An intelligence official in the Kurdish-controlled city of Kirkuk, speaking on condition of anonymity because he is not authorised to talk to the press, said “high value detainees” were believed to be among those captured.

Head of all US forces in the Middle East, General Lloyd Austin, said the mission was conducted with bravery. Photo: Getty

“The Daesh leaders in Hawijah all went missing after the raid. Their offices are closed and nobody knows where they went,” a Hawijah resident said, speaking on condition of anonymity for fear of retribution. Daesh is the Arabic name for IS.

“The group’s top Hawijah leader was detained and another senior leader too. A number of them were killed and several of the people held in that prison were freed,” said another resident of the area.

“The aim of the operation was to free hostages in Daesh custody. They were detained in the former house of a local judge,” the intelligence official in Kirkuk said.

Najmeddin Karim, the governor of Kirkuk province, confirmed that a commando operation was carried out overnight but did not provide details.

Kurdish peshmerga forces control Kirkuk and have long worked closely with the US-led coalition.

The White House was careful to characterise the mission as “assistance” to the Iraqi government, not front line combat.

When press secretary Eric Schultz was asked if he would not deny that this was an American that was killed in a combat role, he said: “I know that some of the language here has very specific consequences.

“I would tell you that this was a special operations, this was a Peshmerga operation supported by US special operations forces.”

– with Jackson Stiles, Anthony Colangelo and AAP