Police say four suicide bombers among 19 killed in Nigeria blasts

At least 15 people were killed when four female suicide bombers detonated their explosives in Maiduguri, northeast Nigeria, police said on Wednesday, in the latest violence to hit the strategic city.

Borno state police commissioner Damian Chukwu told reporters the four struck in the suburb of Molai Kalemari on Tuesday night and that most of the victims were civilian militia manning security posts.

"The bombers detonated IEDs [improvised explosive devices] strapped to their bodies at different locations of the area, killing 19 people, including the bombers," he said.

"A total of 23 people were injured."

Bello Danbatta, a spokesman for the Civilian Joint Task Force (JTF) militia and chief security officer at the Borno State Emergency Management Agency (SEMA), said it appeared his men were the targets.

Two of the bombers blew themselves up at checkpoints manned by militia members, who assist the military with security and sometimes accompany soldiers on operations against Boko Haram jihadists.

"In all we lost 12 of our gallant JTF," he said.

He added, "Civilian JTF have sacrificed their lives to protect their people and the life and property of the citizens of Borno state.

"We sacrificed our life, God willing, we continue to fight this insurgency."

SEMA operatives in face-masks and white overalls were on Wednesday seen removing body parts from the scene of the attacks. Victims were covered with rugs awaiting burial, as local people looked on.

Boko Haram has killed more than 20,000 people and forced some 2.7 million people to flee their homes and has been leading a nine-year-long insurgency against the governments of Nigeria, Niger, Cameroon and Chad.

The group has been pushed out of most of a swathe of land around the size of Belgium that it controlled in early 2015 by Nigeria's army and troops from neighbouring countries in northeast Nigeria.

But insurgents continue to carry out suicide bombings and raids in northeast Nigeria, as well as in Cameroon and Niger.

Young women and girls have frequently been used to attack security checkpoints, as well as civilian "soft targets" such as mosques, markets and bus stations.

Nine people were killed in a string of suicide bomb attacks in the city last month around the Eid al-Fitr holiday marking the end of the Muslim holy month of Ramadan.

The University of Maiduguri, which lies on the edge of the city, has become a frequent target since the start of the year, as it teaches the "western" education despised by the Islamic State group affiliate.