Abu Ibrahim al-Hashimi al-Qurayshi, the leader of the Islamic State (IS) terror group, died when he detonated an explosive device during a US military raid in Syria that aimed to kill or capture him, a Pentagon official said.

On Wednesday night, an IS deputy and some of al-Qurayshi's family members were also killed when the latter detonated the explosive device, a statement issued by the Department of Defense (DoD) said citing the official as saying.

The raid targeted a three-storey residential building on the outskirts of the opposition-held town of Atmeh, which is in northern Idlib province and close to the border with Turkey, the BBC reported.

The region is a stronghold of jihadi groups that are fierce rivals of IS, as well as Turkish-backed rebel factions fighting the Syrian government.

"The professionalism, skill and readiness of our troops — honed through relentless rehearsal — has dealt IS a severe blow and has helped make our country and our fellow citizens safer," Secretary of Defense Lloyd Austin said on Thursday.

Austin said al-Qurayshi, also known as Haji Abdullah who became IS leader in 2019 following the death of his predecessor Abu Bakr al-Baghdadi, provided near constant operational guidance to IS fighters, including the prison break and attack at Hasakah and the slaughter of Yazidis in Iraq.

"He is now off the battlefield and out of command and cannot threaten any more lives," Austin said.

The Secretary praised the US Central Command and US Special Operations Command for their superb support to the planning and execution of this mission.

In a separate press conference also on THursday, President Joe Biden said: "I'm grateful for the immense courage skill and determination of our US forces who skillfully executed this incredibly challenging mission.

"The members of our military are the solid steel backbone of this nation, ready to fly into danger at a moment's notice to keep our country and the American people safe, as well as our allies. I'm also grateful to the families of our service members," he said.

Biden also mentioned the important role of this mission by the Syrian Democratic Forces, saying the DoD will continue to work with them, as well as the Iraqi Security Forces, including the Kurdish Peshmerga, and more than 80 members of the global coalition, to keep pressure on IS.

Also addressing reporters later in the day, Pentagon Press Secrtary John Kirby said that despite some civilian deaths in the compound that resulted when al-Qurayshi detonated an explosive device, "the calculated efforts of our forces succeeded in protecting more than 10 women, children and babies".

The UK-based watchdog group, Syrian Observatory for Human Rights, has put the toll at 13, saying that women and children were killed during the raid.