Russia's media watchdog accused the BBC Thursday of spreading the ideologies of "terrorist groups" via online publications of its Russian service, the latest in a tit-for-tat row over media impartiality.

Islamic State group chief Abu Bakr al-Baghdadi was reported dead on Tuesday, a day after Iraq declared it had driven the jihadists from their one-time biggest stronghold of Mosul.

The Islamic State group swiftly issued a statement via its Amaq propaganda agency blaming a US strike, but the US-led coalition condemned the destruction as a crime against "the people of Mosul and all of Iraq".

The Russian army on Friday said it hit Islamic State leaders in an airstrike in Syria last month and was seeking to verify whether IS chief Abu Bakr al-Baghdadi had been killed.

Islamic State group chief Abu Bakr al-Baghdadi is reported to have abandoned Mosul, leaving local commanders behind to lead the battle against Iraqi forces advancing in the city.