A car bomb in a marketplace in Maiduguri, the northeast Nigerian city that is the birthplace of Boko Haram extremism, has killed at least 56 people.
Sadiq Abba Tijjani, the leader of the Civilian Joint Task Force, said his group recovered at least 56 bodies at the blast site, mostly elderly women who sold peanuts and lemon juice at the market.
Tijjani said they managed to identify 21 of the dead but the rest "were either burnt or damaged beyond recognition."
Other witnesses also estimated the death toll to around 50. Some officials said only 17 people died in the explosion that ripped through the market early on Tuesday.
Witnesses and officials have blamed Boko Haram extremists who have been accused of a series of bomb attacks in the West African nation. The group, which attracted international attention with its April abduction of more than 200 schoolgirls, has scaled up its activities in recent months.
In a statement issued on Monday, UN Secretary-General Ban Ki-moon reiterated the readiness of the United Nations "to support Nigeria as it responds to this challenge in a manner consistent with its international human rights obligations."
Maiduguri, a city of more than 1 million people, has suffered from many strikes. In March, twin car bombs killed more than 50 people at a late-night market where people were watching a football match on a big screen.
Tuesday's explosives were hidden under a load of charcoal in a large vehicle, according to witnesses who spoke on condition of anonymity for fear of reprisals.
Stalls, goods and vehicles were reduced to piles of rubbish. The burnt-out shells of five vehicles and some tricycle taxis marked the site of the explosion.
Trader Daba Musa Yobe, who works near the popular market, said the bomb went off just after the market opened at 8 am, before most traders or customers had arrived.
Witnesses said the death toll could have been even higher was it not for Ramadan, the Muslim month of fasting from sunrise to sunset, which meant fewer people than normal were at the market at that time because they had stayed up late to eat.
Boko Haram has adopted a two-pronged strategy this year of bombing urban areas and conducting scorched-earth attacks in northeastern villages where people are gunned down and their homes burned.
On Sunday, suspected extremists sprayed gunfire on worshippers in four churches in a northeastern village and torched the buildings, killing at least 30 people.
Last week, at least 42 people were killed in three blasts around the country, including 24 people at the biggest shopping mall in Nigeria's central capital Abuja. It was the third blast in as many months in that city. In May, twin car bombs at a marketplace also left more than 130 dead in the central city Jos.
