Fighters from the Islamic State West Africa Province (ISWAP) group attacked the base in the town of Banki in Borno state late Sunday, leading to an intense gun battle with troops, the sources said.

The attackers arrived in trucks fitted with machine guns.

"We lost four troops in the fierce battle which lasted for more than an hour," a military officer told AFP.

Air support had to be called in before the jihadists were "subdued and 20 of them were neutralised," said the military officer.

"The terrorists were determined to infiltrate the base but met their Waterloo," said the second military source, who gave the same toll.

Three trucks were hit by fighter jets and another one was seized along with a dozen rifles, said the second source.

Both sources asked not to be identified as they were not authorised to speak about the incident.

ISWAP has been trying to consolidate its control in the northeast since the death last month of Abubakar Shekau, the leader of rival Boko Haram faction.

Shekau blew himself in his Sambisa forest hideout to avoid capture by ISWAP during the confrontation.

Banki, 130 kilometres (80 miles) southeast of Borno state capital Maiduguri, houses some 45,000 people displaced by the jihadist conflict in a sprawling camp.

Boko Haram has launched several attacks in and around Banki, targeting troops and the displaced.

The 12-year-old jihadist conflict has killed 40,000 people and displaced around two million from their homes in northeast Nigeria alone.

The violence has spread to neighbouring Niger, Chad and Cameroon, prompting a regional military coalition to fight the insurgents.