For the first time in five years, Islamic State leader Abu Bakr al-Baghdadi has appeared in a video released by terror group's media arm Al Furqan.

In the video published on Monday, Islamic State's media network said it was a video message from its leader. Baghdadi said in the video that the group would seek revenge for the killing and imprisonment of its militants as he praised suicide bombers who carried out attacks on churches and hotels in Sri Lanka last week.

In the unverified video, a bearded man with Baghdadi's appearance sitting cross-legged on the floor gives an 18-minute address. Several aides also appear in the video but their faces have been covered or blurred.

"The battle for Baghouz is over," the man said. "There will be more to come after this battle."

Written script at the start of the video dated it to earlier in April.

Commenting on the video, Rita Katz, Director of SITE Intelligence Group which follows terrorist attacks across the globe, said this is the first time he is shown in a video since his July 2014 sermon at the Great Mosque in Mosul, Iraq. In the 2014 video, he had declared the captured territory in Syria and Iraq an Islamic "caliphate".

He was reported killed or injured multiple times since then.

"The video shows Baghdadi in a casual conversational setting with others (their faces blurred). He talks about war against "Crusaders" and about battles in Baghouz, Syria being over, indicating that this interview was filmed somewhat recently," she said.

She further said, "In the video, titled “In the Hospitality of the Emir of the Believers,” Baghdadi praises SriLanka attackers over images of the attackers/attack (though not in the visual interview section; the audio may have thus been added via a later recording)--calling it revenge for Baghouz."

His last voice recording to his supporters was released in August, eight months after Iraq announced it had defeated IS and as US-backed forces closed in next door in Syria.

, sitting cross-legged on a cushion and addressing three men whose faces have been blurred.

But he insisted that IS's operations against the West were part of a "long battle," and that IS would "take revenge" on members who had been killed.