In the video, Baghdadi, who has not been seen after announcing the "caliphate" across his group's conquered parts of Syria and Iraq in 2014, admits defeat at the group's last stronghold in Syria and refers to the regime changes in Algeria and Sudan where long-time rulers have been forced to step down, the BBC reported.

The video also mentions the Easter Sunday carnage in Sri Lanka - which the IS has claimed responsibility for, but in audio form towards the end of the video with no image of Baghdadi alongside, which indicates it might have been added later.

The 18-minute video, which IS says was shot this month, was posted on the group's al-Furqan media network.

"The battle for Baghouz is over," says Baghdadi, an 47-year-old Iraqi whose real name is Ibrahim Awwad Ibrahim al-Badri and was last heard in an audio recording last August, says in the video, referring to the group's last territory in violence-torn Syria which the Kurdish militia claimed to have re-captured.

"There will be more to come after this battle," he is heard saying.