Boko Haram, in a video released online on Tuesday, rejected claims from Nigeria’s military that it has been routed by a four-nation offensive. The video does not show the group’s leader, Abubakar Shekau.

The unidentified speaker, his face obscured by a headscarf, instead called Nigeria, Cameroon, Chad and Niger, who have been battling the Islamists, “the lying coalition partners.”

“Most of our territory is still under our control,” said the speaker in the 10-minute message which was posted on the video-sharing site YouTube.

The video bears the logo “Islamic State in West Africa” and follows the Nigerian militants’ pledge of allegiance in an audio message in March to the IS group, that has overrun large parts of Syria and Iraq.

The message is the first video released by Boko Haram since February, when Shekau was shown in high definition footage and vowed to disrupt Nigeria’s elections.

He has featured prominently in most of the group’s videos over the last three years and his absence in the latest message will likely stir further debate on his whereabouts or possible death.

Nigeria’s military has previously claimed to have killed Shekau only for him then to pop up on another video. The authorities have explained such appearances away by saying that the role of “Shekau” was filled by various lookalike insurgents.

Analysts have typically viewed Boko Haram as a factionalised group, with a relatively weak central command structure.

It is possible that the movement towards the IS group in the Middle East followed a split among the Nigerian militants and that Shekau – if he is still alive – has lost a degree of control.

But solid information concerning power struggles within Boko Haram has been scant to non-existent, so the current make-up of the group is largely unknown.

The speaker in the new message appears in front of two pick-up trucks, with four other gunmen visible in the background.

He speaks in the Hausa language that is dominant in Northern Nigeria with Arabic and English subtitles shown below.

An AK-47 rifle rests on his chest as he seeks to rebuke the claims of successes made in recent weeks by the coalition.

“The armies claim through the media that they captured our towns and that they assaulted Sambisa (forest) and defeated us,” he said, referring to the bushland area in Nigeria’s northeast Borno State that has been an Islamist stronghold.

“I swear by Allah that I am talking right now from Sambisa... Here in Sambisa you can travel more than four to five hours under the black flag of Islam by car or by motorbike.”

“We are uncountable in Sambisa. We are thousands of Mujahedeen here,” he further said, dismissing claims of the insurgents’ defeat as “false propaganda”.

The latter parts of the video include depictions of gruesome violence, including executions of apparent civilians and one man in a Nigeria police uniform, who are shot at close range.

“President of Nigeria Jonathan" is mentioned, referring to Goodluck Jonathan, who handed over power to Muhammadu Buhari last Friday, two months after the latter's victory in elections on March 28.

In his inaugural speech as president on Friday, Buhari described Boko Haram as “mindless” and “godless” and vowed to demolish the group during his tenure.

But the Islamists struck hours after Buhari was sworn in, launching a series of attacks since Saturday in Borno’s capital Maiduguri, deploying suicide bombers and fighting armed with rocket-propelled grenades. (AFP)

•Photo shows Boko Haram