US can't confirm if IS chief is dead

The Syrian Observatory for Human Rights has "confirmed information" Islamic State's Abu Bakr al-Baghdadi is dead, but the US says it can't confirm his death.

The death of Abu Bakr al-Baghdadi, leader of Islamic State, has not been widely confirmed. (AAP)

The US-led coalition battling Islamic State does not have concrete information about whether Islamic State leader Abu Bakr al-Baghdadi is dead or alive, the senior US general leading the campaign says.

"Despite all the helpful reports to us from every source imaginable, I'm unable to confirm or deny either where he is or whether he is alive or dead. Let me just say for the record my fervent hope is it is the latter," Lieutenant General Stephen Townsend told a news briefing on Tuesday

The Syrian Observatory for Human Rights said it had "confirmed information" that Islamic State leader Abu Bakr al-Baghdadi has been killed.

Russia's defence ministry said it may have killed Baghdadi when one of its air strikes hit a gathering of Islamic State commanders on the outskirts of the Syrian city of Raqqa, but Washington said it could not corroborate the death and Western and Iraqi officials have been sceptical.

Reuters could not independently verify Baghdadi's death.

Baghdadi's death, which has been frequently reported since he declared a caliphate from a mosque in the Iraqi city of Mosul in 2014, is one of the biggest blows yet to the jihadist group, which is trying to defend shrinking territory in Syria and Iraq.