Islamic State leader Abu Bakr al-Baghdadi may have been killed in an air strike by Russian forces in on the outskirts of Raqqa in Syria, last month, unconfirmed reports from Moscow said.
The Russian defence ministry said on its Facebook page that it was checking information that Baghdadi was killed in the strike, launched after Russia received intelligence about a meeting of Islamic State leaders.
"On May 28, after drones were used to confirm the information on the place and time of the meeting of IS leaders, between 00:35 and 00:45, Russian air forces launched a strike on the command point where the leaders were located," the statement said.
"According to the information which is now being checked via various channels, also present at the meeting was Islamic State leader Abu Bakr al-Baghdadi, who was eliminated as a result of the strike," the ministry said.
The Russian defence ministry statement said the strike was believed to have killed several other senior leaders of the group in addition to Baghdadi, as well as around 30 field commanders and up to 300 of their personal guards.
Western sources said they could not corroborate the death while Iraqi officials said they were sceptical about reports about the secretive leader.
Baghdadi, who lead his fighters on a sweep through northern Iraq and declared a caliphate to rule over all Muslims from a mosque in Mosul in 2014, has several times been reported killed or wounded.
If the report proves true, it would be the biggest blow yet to Islamic State, which is trying to defend its shrinking territory and influence against an array of forces both regional and global in both Syria and Iraq.
"His death has been reported so often that you have to be cautious till a formal Daesh (the Arab acronym for ISIS) statement comes," a European security official said.
Pentagon spokesman and US Navy Captain Jeff Davis said, "We have no information to corroborate those reports."
However, a Reuters report quoting a colonel with the Iraqi national security service said Baghdadi was not believed to have been in Raqqa at the time of the strike in late May. The officer also told Reuters that the possibility was that one of Baghdadi's aides might have been killed rather than Baghdadi himself.
Baghdadi, he said, was believed to be operating cautiously in the border area between Iraq and Syria with just a handful of close aides, and avoiding using telecommunications equipment to evade surveillance.
Iraqi intelligence officials said the authorities were checking the report and would announce his death if it received "solid confirmation".