Convoys have increasingly come under attack from Islamic State West Africa Province (ISWAP) jihadists in the northeast where soldiers are battling to end a 12-year Islamist insurgency that has killed more than 40,000 civilians.

On Saturday four soldiers, including a military commander, were killed when ISWAP fighters ambushed them as they moved to provide reinforcements during a jihadist attack on Askira Uba town in Borno state, the army said in a statement.

"Sadly, a gallant senior officer Brigadier General Dzarma Zirkusu and three soldiers paid the supreme sacrifice in a very rare display of gallantry as they provided reinforcement in a counter offensive against the terrorists," the statement.

Troops supported by fighter jets "neutralised several" jihadists in the fight and destroyed many of their vehicles, added the statement issued by the military's spokesman.

Another three soldiers were killed on Friday when ISWAP fighters ambushed a military convoy in neighbouring Yobe state, according to two military sources.

Scores of jihadists opened fire on the convoy with heavy guns in an ambush at Tamsu Kawu village along the 120-kilometre highway linking Maiduguri and Yobe state capital Damaturu, the two sources told AFP.

"We lost three soldiers in the ambush from ISWAP terrorists," said one of the military officers.

The militants seized a military vehicle in the attack, said the military officer.

His account was supported by a second military officer who gave the same toll.

The attacks happened as the military claimed a string of successes against the jihadists, including raids on their camps.

On September 17, at least 16 Nigerian soldiers were killed in an ISWAP ambush on the highway linking Maiduguri and the garrison town of Monguno in the Lake Chad region.

A week later, eight soldiers died when the jihadist group ambushed a military convoy near the town of Dikwa in the same area.

ISWAP has been consolidating territory in the Lake Chad area since rival Boko Haram commander Abubakar Shekau was killed in fighting between the two jihadist forces earlier this year.

Since 2019, soldiers have shut down some smaller army bases and moved into larger, fortified garrisons known as "super camps" in an attempt to better resist militant attacks.

But critics say the "super camp" strategy has also allowed militants more liberty to move around in rural areas and left travellers more vulnerable to kidnap.

The conflict which has displaced around two million in the northeast spilled into neighbouring countries, prompting a regional military coalition fighting the Islamist militant groups.