At least 12 people were killed on Wednesday when two female suicide bombers blew themselves up in a market in the northern Nigerian town of Chibok where Boko Haram militants abducted more than 200 girls almost two years ago, police and residents said.

Boko Haram has been waging a six-year armed campaign in Nigeria’s remote north to build an Islamic state. Thousands have been killed and more than two million people displaced by the campaign.

There was no immediate claim of responsibility but the attack bore the hallmarks of Boko Haram, which has been using suicide bombers since the army expelled the group from much of the northern territory it had captured previously.

“Two veiled girls suspected to be suicide bombers entered Chibok market at about 12:54 pm today,” a police official said, asking not to be named.

“Afterwards we heard an explosion at the heart of the market and people fled. Some minutes later another blast came just at the edge of the market,” he said.

The official said he had counted eight bodies at the market, while four others had died on the way to the hospital. Some 15 people were treated in hospital, he added.

Musa Pagu and Ishaya Ali, members of a civilian vigilante group that helps maintain order in the area, also said 12 people had been killed.

In April 2014, Boko Haram militants raided a Chibok school while girls were taking exams. They loaded 270 of them onto trucks and disappeared, though about 50 escaped soon afterwards.

There was a global outcry and threats by Boko Haram to sell the girls. Nigeria's then-president Goodluck Jonathan came under heavy criticism for his government’s slow reaction.

His successor Muhammadu Buhari, who pledged during his election campaign to end the insurgency, said in December he was open to negotiating with Boko Haram for the return of the girls if credible representatives of the group could be identified.

Nigerian troops have recaptured most of Borno state, where Chibok is situated and where the insurgency started, helped by forces from Chad, Niger and Cameroon, who themselves were increasingly being targeted by the militant Islamists.

Boko Haram has since reverted to raiding villages for provisions or hitting soft targets such as places of worship and markets. The group operates mainly around Lake Chad, the Sambisa forest reserve and the mountainous region bordering Cameroon. (Reuters)

•File Photo shows Chibok parents weeping as a result of the abduction of their schoolgirls. Now, Boko Haram has dealt the town another devastating blow.

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