Russia can't confirm IS head Baghdadi dead.

Leader of the Islamic State group, Abu Bakr al-Baghdadi, delivering a sermon at a mosque in Iraq during his first public appearance. Source: Militant video

Russian Foreign Minister Sergey Lavrov says he can't definitively confirm the death of the Islamic State group's leader in a Russian airstrike.

The Russian Defense Ministry claimed earlier on Friday that IS leader Abu Bakr al-Baghdadi was killed in a Russian strike in late May, adding that the information about his death was still "being verified through various channels."

Asked about the claim at a news conference in Moscow, Lavrov said: "I don't have a 100 per cent confirmation of the information."

He added on a cautious note that if al-Baghdadi's death is confirmed, its importance mustn't be overestimated.