Two bomb blasts ripped through mosques in northeast Nigeria on Friday, killing at least 55 people and injuring more than 100, as Boko Haram fighters seized a town in neighboring Cameroon.

The attacks in Maiduguri, Yola and Kerawa again underlined the persistent national and regional threat from the Islamist militants, despite military claims of gains.

Four people were killed when three suicide bombers blew themselves up in a suburb of the northeastern Nigerian city of Maiduguri, the army said on Wednesday.

"The explosions occurred at three-minute intervals and seven people were confirmed dead, including the three suicide terrorists," said army spokesman Colonel Sani Usman.

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," Defense Headquarters in Abuja said of Thursday night's attacks.

A suicide bomber hit a military checkpoint on the outskirts of the northeastern Nigerian city of Maiduguri on Monday, in the latest in a string of attacks blamed on Boko Haram Islamists.

The blast happened at about 12:10 pm (1110 GMT) at the Jimtilo checkpoint, as passengers arriving in Maiduguri were being screened, two civilian vigilantes told AFP.

At least 14 people were killed in a suicide bomb attack at a crowded market in Chad's capital on Saturday just days after Boko Haram claimed a previous bombing in the city that left 38 people dead.

The attack in N'Djamena by a man disguised as a woman in a full-face veil came after a botched bombing in the capital of Nigeria's Borno state, Maiduguri, which killed two pedestrians.

At least five people have been killed and 10 wounded after a suicide bomber blew himself up outside a leprosy hospital on the outskirts of the northeast Nigerian city of Maiduguri, emergency services said.

The bomber, who tried to gain access to the hospital, detonated his explosives outside the building at around 5:30 pm (1630 GMT) on Saturday.

At least 20 people were killed Monday when a young female suicide bomber detonated her explosives at a bus station in Maiduguri, northeast Nigeria, in an attack likely to be blamed on Boko Haram.

The blast happened near a fish market in the Baga Road area of the city, which has been repeatedly targeted in recent weeks by shelling, bombs and suicide attacks.

Nigeria's military on Monday said it had begun shifting the command center for its battle against Boko Haram from the capital to Maiduguri in the northeast, following a directive from President Muhammadu Buhari.

Buhari announced the move in his inaugural speech on May 29, saying the Islamist insurgents would not be defeated until military command and control was transferred to the city at the heart of the uprising.

The death toll from a blast in the northeast Nigerian city of Maiduguri has risen to 18, a civilian vigilante assisting the military against Boko Haram told AFP on Thursday.

"We retrieved 18 dead bodies from the scene and many people with injuries," Danlami Ajaokuta said of the explosion on the city's Baga Road, which happened at about 5:30 pm (1630 GMT) on Wednesday.

At least six people were killed on Wednesday in an explosion in the northeast Nigerian city of Maiduguri, a civilian vigilante assisting the military against Boko Haram and a witness told AFP.

"We have so far recovered six dead bodies. We are still working at the scene, so the casualties may rise," said Danlami Ajaokuta of the blast on the Baga Road, which happened at 5:30 pm (1630 GMT).