At least nine Nigerian soldiers were killed and several others injured when their convoy struck a landmine and came under fire in Borno state in northeastern Nigeria, two security sources said on Monday.

The attack took place on Sunday near Bindundul village, about 20 kilometres (12 miles) from Kareto, an area where Islamic State West Africa Province fighters operate freely and often set up checkpoints, according to a military source from the Damasak brigade.

"The terrorists planted a mine that our soldiers stepped on. Unfortunately, about nine soldiers died instantly, while five others were seriously injured," said Abba Kaka Tuja, a member of the Civilian Joint Task Force involved in the rescue operation.

He added that an armoured vehicle was destroyed when the mine detonated, followed by sporadic gunfire from militants.

The soldiers were traveling from Maiduguri to Damasak, the headquarters of Mobbar Local Government Area, when the attack occurred around 1600 GMT, Tuja said.

Military officials did not immediately respond to requests for comment.

Nigeria’s northeast, where ISWAP fighters and Boko Haram have intensified attacks in recent months, targeting military convoys and civilians, is the country’s most conflict-prone region.

Other areas are also tense. The United States carried out a strike against Islamic State militants in the northwest late last month.