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The attackers stole weapons before looting shops in a nearby town, military sources said on Tuesday.

The raids late on Monday came a day after 30 people were killed in a triple suicide bombing that also bore the hallmarks of the Boko Haram group.

"Fifteen bodies of soldiers have so far been recovered in a search and rescue operation," a military officer, who asked not to be named, told AFP after the latest attack.

"This figure could change as the operation is still ongoing and many troops remain unaccounted" for.

Boko Haram's decade-long campaign of violence has killed some 27,000 people and displaced about two million in Nigeria.

The latest assault targeted a base outside the town of Gajiram, 80 kilometres (50 miles), north of the Borno state capital Maiduguri.

The assailants were suspected to be from an Islamic State group-affiliated Boko Haram faction known as the Islamic State West Africa Province (ISWAP).

They arrived on nine armoured trucks and "dislodged troops from the base after a fight," a security source told AFP.

The attackers carted away weapons and vehicles and set fire to the base, causing substantial damage, the sources added.

Residents said they then drove into the town and looted shops, shooting into the air.

Their presence forced residents to flee into the bush while others shut themselves in their homes.

The gunmen "stayed for almost five hours. They broke into the shops and looted food supplies and provisions," Gajiram resident Mele Butari told AFP.

"They didn't hurt anyone and they made no attempt to attack people who fled into the bush or hid indoors."

Soldiers were seen returning to the town from the bush Tuesday morning.

Gajiram lies on the highway linking Maiduguri and the garrison town of Monguno, 55 kilometres away. Gajiram and its army base have been repeatedly attacked by insurgents. In June last year, ISWAP killed nine soldiers there.

ISWAP has targeted dozens of military bases since last year, killing scores of soldiers.

Last week, several troops were killed in an ISWAP attack on a remote base in Kareto village, near the border with Niger, according to military sources.