The country's military earlier denied the abduction and killing of officer M. Uba by militants as a "fake narrative"

Islamic State West Africa Province (ISWAP) militants have claimed that they captured and executed a Nigerian brigadier general during a deadly ambush on a military convoy in the country's troubled northeastern Borno State.

Last week, the Nigerian Army said a convoy led by Brigadier-General M. Uba of the 25 Task Force Brigade came under "sudden and heavy insurgents fire" while returning from a patrol near Wajiroko late on Friday.

According to the military, two soldiers and two members of the Civilian Joint Task Force were killed in the encounter. It denied that Gen. Uba was captured by the militants during the attack, dismissing circulating reports as a "fake narrative."

The ISWAP's claims were carried in a statement published by its affiliate Al Amaq news agency on Monday. The group called the army's denial an "outright lie," AP reported. Reuters also said the militants claimed responsibility for the ambush and stated that it killed the army officer following an interrogation.

ISWAP emerged in 2016 after a split with Boko Haram, triggered by ideological and leadership disputes. Boko Haram's leader at the time, Abubakar Shekau, was criticized by Islamic State's central command for indiscriminate attacks on Muslim civilians. He was replaced by Abu Musab al-Barnawi, prompting a division between the factions.

Violence linked to the insurgent groups has continued to destabilize Nigeria's northeast, displacing millions and claiming thousands of lives.

This year alone, suspected ISWAP fighters have repeatedly targeted military positions in Borno, including a January raid that killed at least 20 soldiers at an army base in Malam Fatori. Last month, four soldiers were killed and five wounded when troops repelled a coordinated attack by Islamist insurgents in Ngamdu. In March, the jihadists mounted coordinated attacks on bases in Wajiroko and Wulgo near the Cameroon border.

Africa's most populous country has long struggled to contain insecurity fueled by terrorist groups and criminal gangs. In a separate incident on Monday, gunmen stormed a government girls' boarding school in northwestern Kebbi State, killing the vice principal and abducting about 25 female students.