Lavrov added on a cautious note that if al-Baghdadi's death is confirmed, its importance must not be overestimated.
The Russian Defense Ministry said on its Facebook page that it was checking information that Baghdadi was killed in the strike, which it launched after receiving intelligence that a meeting of IS leaders was being planned.
But a spokesman for the United States-led coalition against ISIS said he could not verify that al-Baghdadi had been killed.
Later at the meeting of President Vladimir Putin's security council, Russia's Defence Minister Sergei Shoigu gave different figures of jihadists killed in the strike, according to the Kremlin. During Russia's wars against separatist insurgents in the region of Chechnya, reports about the unconfirmed death of the same enemy commander were repeatedly churned out, Sergey Aleksashenko, Russian domestic affairs expert at the Brookings Institution says.
There have been previous reports of Baghdadi's death that later turned out to be false.
Assaults on Raqqa have been launched by troops of the Assad regime, backed by Russian air strikes and Iranian and Lebanese Hezbollah forces on the ground; a Kurdish and Arab force with U.S. and British special forces and backed by American warplanes and an Arab and Turkman contingent supported by the Turks.
In November 2016, the Iraqi military claimed that al-Baghdadi fled from Mosul during the government forces' operation to re-capture the city, which has been controlled by terrorists since 2014.
"We recommend proceeding with caution" toward the claim that al-Baghdadi, who declared an ISIS caliphate in Syria and Iraq in June 2014, has been killed", one official told The Washington Times on Friday.
If the report does prove true, it would be one of the biggest blows yet to Islamic State. "The infrastructure or the network on the ground might be hit, but this group is a cell-generating network".
According to an official Iraqi government document, al-Baghdadi was born in Samarra in Iraq in 1971. Extremists linked to the group have proliferated and murdered hundreds in London, Ankara, Beirut, Brussels and Paris as well as in Iraq, Syria and elsewhere. Dead or alive he's already passed into legendary status for his followers and the concept of ISIS (as opposed to the physical reality of their armies and infrastructure) has taken root across the internet and in secret meetings in mosques and other gathering places around the world.
# On June 9, 2016, Iraqi State TV claimed that al-Baghdadi had been wounded in a USA airstrike in Northern Iraq.
"It just doesn't really make that much sense", Damon said. "The group does not reply on him alone for guidance".
The State Department had previously offered $25 million for information that helps the US determine the location of al-Baghdadi, or arrest and convict him.
Islamic State fighters are close to defeat in the twin capitals of the group's territory, Mosul in Iraq and Raqqa in Syria.
The Britain-based Syrian Observatory for Human Rights reported airstrikes south of Raqqah May 28 that killed 18 people, including 10 Islamic State fighters.
There was no Russian airstrike on Raqqa on May 28, according to the SOHR's head, Rami Abdurrahman. He added that all the top leaders of Islamic State are thought to be in an area between the Iraqi border and Deir Ezzor, which is about 85 miles (140 kilometers) southeast of Raqqa.
"Forces of the USA -led anti-I.S. coalition have repeatedly issued strikes on Syrian government forces fighting I.S. near the Jordanian border".
It said the attack had targeted a meeting of IS leaders in the southern outskirts of the group's de facto capital of Raqqa, northern Syria.