"According to the Russian Defense Ministry, it is highly likely that Daesh leader al-Baghdadi was eliminated as a result of a Russian Aerospace Forces strike on the terrorists' command post in the southern suburb of the city of Raqqa in late May this year," Russian Deputy Foreign Minister Oleg Syromolotov said.
The "information is now verified through various channels," Syromolotov told the official Sputnik news agency.
"I have got nothing (to report)," Tass news agency quoted her as saying.
Last Friday, the Russian Defense Ministry reported that Baghdadi had been presumably killed by the airstrike on Raqqa's southern suburbs carried out by Russian warplanes.
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According to the ministry, the airstrike was conducted on May 28 on a command post where the Islamic State leaders were discussing exit routes for militants from Raqqa through the so-called southern corridor.
There have been a number of previous reports of Baghdadi's death or him being critically injured by US-led coalition air strikes.
Baghdadi has not been seen in public since proclaiming himself "caliph" in the Iraqi city of Mosul three years ago.
In October 2011, the US officially designated Baghdadi as a "terrorist". It has offered a reward of up to USD 25 million for information leading to his capture or death.
The ISIS terror group is known for imposing a hard-line form of Islam that has included stonings, amputations and beheadings.