Nigerian President Bola Tinubu confirmed on Tuesday that terrorists had killed an army brigadier general, the highest-ranking military official to die in the long-running conflict since 2021.

ISWAP claimed on Monday that it ambushed and killed a senior officer in the northern Chad region days earlier, in a post alongside a picture of Brigadier General Musa Uba.

"I am depressed with the tragic death of our soldiers and officers on active duty. May God comfort the families of Brigadier General Musa Uba and other fallen heroes," Tinubu said in a statement.

The Nigerian army initially dismissed reports that Uba had been captured in the ambush.

According to the army and a United Nations report, two soldiers and two members of a self-defence group were killed in the attack.

ISWAP broke away from the Boko Haram terrorist group in 2016 and is focused on attacking the Nigerian army.

Terrorist attacks have killed more than 40,000 people and displaced nearly two million in northeastern Nigeria since 2009, and has spread to neighbouring Niger, Chad and Cameroon.

Uba is the second senior officer killed by terrorists in four years, after General Dzarma Zirkusu, who died in November 2021.