Clashes between Nigeria’s military and Islamist extremist group Boko Haram in two northeastern towns have left at least 35 people dead, most of them insurgents, the army said Monday.

Clashes between Nigeria's military and Islamist extremist group Boko Haram in two northeastern towns have left at least 35 people dead, most of them insurgents, the army said Monday.

The clashes broke out after attacks on soldiers and a police station, according to the military, and occurred as security forces wage an offensive in the region aimed at ending a four-year Islamist insurgency.

A clash in the town of Bama sparked by an attack on a police base "led to the death of one policeman and 17 Boko Haram terrorists," a military statement said.

Fighting in the town of Malam Fatori after an attack on troops "led to the death of two soldiers and 15 Boko Haram terrorists," it said. Both clashes occurred on Sunday.

According to the military, the insurgents were armed with "sophisticated weapons" and explosives during the attacks. Both Bama and Malam Fatori are located in Nigeria's Borno state, Boko Haram's home base.

The statement said soldiers had recovered weapons including 10 AK-47 rifles, bombs and three RPG tubes, among others, after the clash in Bama.

"The situations in both places have returned to normal," the statement said.

Borno, badly hit by insurgent attacks as well as heavy-handed  military raids, is one of three states currently under a state of emergency while security forces pursue the offensive.

The military has claimed major successes, saying troops have pushed out the insurgents. The number of attacks has appeared to have dropped since the offensive began, but violence has nevertheless continued.

The military's version of events has been difficult to verify since the security forces cut phone networks in the northeast, and access to remote areas is increasingly limited.

The military says it has restored phone connections to a number of areas, but service remains spotty.

Violence in recent weeks in the northeast has included three deadly school attacks as well as a clash between insurgents and a vigilante group that recently formed with the encouragement of the military.

There have also been recent attacks outside the areas covered by the state of emergency. 

Bomb blasts ripped through a mainly Christian area of Kano, the largest city in northern Nigeria, a week ago, killing at least 24 people and shattering a recent lull in insurgent attacks there.

The insurgency is estimated to have claimed more than 3,600 lives since 2009, including killings by the security forces.

Boko Haram has claimed to be fighting for the creation of an Islamic state in Africa's most populous nation and largest oil producer, though the group is believed to have a number of factions with varying aims.

Nigeria's 160 million population is roughly divided between a mainly Christian south and mostly Muslim north.