MAIDUGURI - At least 10 people were killed and 39 others injured when four suicide bombers blew themselves up in the city of Maiduguri, northeast Nigeria, the military said on Friday.

"So far it has been confirmed that 14 people have lost their lives, including the suicide bombers, while 39 people were wounded," Defence Headquarters in Abuja said of Thursday night's attacks.

Meanwhile, suspected Boko Haram fighters killed 11 people during attacks on three villages in the northeast Nigerian state of Adamawa, a lawmaker and local official said on Friday.

The attacks on Wednesday evening in Bitiku and Kubu left four dead, while seven were killed early on Thursday morning in Kirchinga. The three villages are in the north of Adamawa state, near the town of Madagali and the border with Borno state, which has been worst hit by the insurgency.

Boko Haram militants have increasingly used suicide bombers to target civilians, including in Maiduguri, where on September 20 at least 117 people were killed in a wave of attacks.

Locals and one police officer in the Borno state capital said initially there were seven blasts in the Ajilari Cross area of the city, with at least two bombs were strapped to teenage girls.

The military said on Friday: "Although details are still sketchy, suffice to state that four Boko Haram terrorists suicide bombers detonated their vests simultaneously.

"Three of the terrorists (struck) in the same area and the fourth detonated in front of a mosque."

Ajilari Cross, near Maiduguri airport and a military base, was one of several places in the city also hit 10 days ago, spreading fears of more carnage over the recent Eid al-Adha festival.

Nigeria's military has claimed a series of successes against Boko Haram in recent weeks, which has led many to fear an increase in attacks against civilians in the restive northeast.

Amnesty International said on Wednesday more needed to be done to protect ordinary citizens, with at least 1,600 killed in Boko Haram violence in Nigeria, Cameroon, Chad and Niger since June.

The conflict has claimed more than 1,260 lives in Nigeria alone since Muhammadu Buhari took office as president on May 29, according to an AFP tally.

At least 17,000 people have been killed - 3,500 of them this year, according to Amnesty - and more than 2.5 million made homeless since the Boko Haram insurgency began in 2009.