The US-led coalition battling the Islamic State (IS) militant group said Friday it could not confirm the death of IS leader following reports by the Russia army that he might have been killed.

"We cannot confirm these reports at this time," said US Army Colonel Ryan S. Dillon, spokesman for the coalition's Operation Inherent Resolve.

The Russian army said earlier that it hit IS leaders in an air strike in Syria last month and was seeking to verify whether IS chief Abu Bakr al-Baghdadi had been killed.