At least 16 people died in a double suicide bombing near a large camp for people made homeless by years of Boko Haram violence, Nigeria's emergency services and locals said Monday.
The bombing was one of a series of attacks in the conflict-hit region on Sunday which killed a total of 24 people, most of them civilians.
In the attack, which took place on Sunday evening, two women blew themselves up in Kofa village which houses a large camp for those displaced by Boko Haram violence, the National Emergency Management Agency (NEMA) said.
"They killed 16 people," said regional NEMA spokesman Abdulkadir Ibrahim. Kofa lies about 15 kilometres (nine miles) southeast of Maiduguri, capital of Borno state.
Local residents gave an initial toll of 12 or 13 dead but the spokesman said three of the wounded had died of their injuries in hospital.
- Second attack by female bombers -
At around the same time, two more explosions occurred inside the nearby Dalori 2 camp which is home to some 10,000 people, he said, indicating it was caused by another two female bombers.
Several people were wounded but only the attackers died, he said, without saying how many were hurt.
Dalori is home to two camps which together provide shelter for some 50,000 people displaced by the violence between Boko Haram and the Nigerian army.
It is one of the largest camps for internally displaced people (IDP) in this remote region.
It is not the first time Boko Haram has tried to target the camp: in January last year, at least 85 people were killed when insurgents rampaged through communities near Dalori.
The latest attack is the most deadly in Nigeria since June 8, when 11 people were killed in a rare combined gun and suicide attack in the Jiddari Polo area of Maiduguri.
- A bloody weekend -
Elsewhere on Sunday evening, Boko Haram militants raided Gumsuri village near Chibok in eastern Borno state, killing five civilians.
But the gunmen were challenged by local vigilantes who engaged them in a gunbattle "killing 12 of them and arresting six others," said local tribal chief Ayuba Alamson in an account corroborated by the vigilantes.
Several hours earlier, three soldiers were killed in an ambush by militants near Wajirko village, 150 kilometres (90 miles) from Maiduguri, a local vigilante said.
Also at the weekend, residents from five villages near Maiduguri fled their homes after receiving death threats from Boko Haram following a raid by the army last month.
The Islamists accused the villagers of passing "vital information" to the army and threatened to "kill everyone" if they didn't leave the area, local residents said.
The spate of bombings underlines the threat still posed by the jihadists, despite official claims they are a spent force.
Since the start of Boko Harm's uprising in 2009, at least 20,000 people have been killed since and more than 2.6 million made homeless, many of whom are facing severe food shortages or starvation.