Two helicopters are said to have landed in Hmeirah before taking off seven minutes later, with only a few shots fired during the operation.

The Syrian Observatory for Human Rights say an ammunition depot and several positions linked to Iran's military presence in Syria were among the targets.

Some fighters are said to be already in Russia readying to join the fight in Ukraine, though it is not immediately clear how many combatants have been recruited.

A senior White House official says Abu Ibrahim al-Hashimi al-Qurashi detonated a bomb during the raid on the house where he was staying, killing members of his own family, including women and children.

Pentagon spokesman John Kirby says there were no US casualties.

The brazen jailbreak attempt and ensuing clashes left more than 180 dead in the jihadists' most high-profile military operation since the loss of their 'caliphate' nearly three years ago.

Some of the estimated 3,500 IS prisoners inside the facility have already been bused out to other detention centres in recent hours.

The prosecution says this is the first time charges are being brought in Sweden for the war crime of using a child soldier.

A number of girls are reported to have been recruited into fighting, some of them allegedly by force.

The new decree, which state media said came into effect on Monday, effectively forces Ahmed Badreddin Hassoun, appointed as grand mufti by Assad in 2004, into retirement.

The two back-to-back airstrikes near the town of Baghuz were ordered by a classified American special operations unit tasked with ground operations in Syria, according to the report.

There was no immediate claim for the bombing but moments later shelling by government forces killed eight people in the Idlib region controlled by groups that have claimed such attack in the past.