Bomb blasts killed at least 50 people on Saturday in Maiduguri, in Nigeria's northeast, in the worst attacks there since armed fighters tried to seize the city in two major assaults earlier this year. The bombings came amid reports that Boko Haram has pledged allegiance to the Islamic State of Iraq and the Levant (ISIL).
There was no immediate claim for the bombings but they bore the hallmarks of the group Boko Haram, which has been waging a six-year insurgency to carve out an Islamic state in Africa's biggest economy.
President Goodluck Jonathan, who is seeking re-election on March 28, has been heavily criticized for failing to crush the group. The vote was postponed for six weeks from Feb. 14 for security reasons.
Around noon on Saturday, a tricycle rider detonated a bomb after being prevented from entering a fish market on the Baga road in the west of Maiduguri, Mohammad Ajia, a trader at the market said after fleeing the scene.
A second blast hit an area known as the Monday market shortly afterwards before a car bomb exploded by a bus station near a Department of State Security (DSS) office, according to a civilian member of a joint task force.
"We've received 50 dead bodies from the blast scenes and 36 injured people," Salisu Kwaya Bura, chief medical officer of Borno Specialists Hospital, told reporters.
The number of wounded was well above 36 as more had been taken to two other hospitals, a hospital source said.
"Men from the anti-bomb squad came a few minutes after the blast to comb the scene ... I saw five mangled bodies being put in vehicles," Aliyu Musa, a resident near the DSS office, said.
In other developments, Boko Haram on Saturday pledged allegiance to ISIL, which controls swathes of territory in Iraq and Syria, Reuters reported quoting the monitoring group SITE.
"We announce our allegiance to the Caliph ... and will hear and obey in times of difficulty and prosperity," SITE quoted Boko Haram as saying in a video purporting to be from the group.
Maiduguri is the capital of Borno state and birthplace of Boko Haram, which has long coveted the city as a capital for the state it wants to create. The fighters tried to seize Maiduguri at the end of January and again in early February.
Boko Haram overran a territory the size of Belgium last year, which Nigeria's ill-equipped army has struggled to take back, and the group gained worldwide notoriety in April when its members kidnapped more than 200 schoolgirls.
Since the election delay, Chadian troops cooperating with the Nigerians have reclaimed some important towns in Borno. The army has also been able to push the militants out of some territories in neighboring Adamawa and Yobe states.
On Saturday, Nigeria's army said it had retaken two more constituencies in Borno state.
"With the capture of Mafa, Marte LGAs (local government areas), and the Chadian troops holding fort in Dikwa, the international route from Nigeria, Cameroon, Chad and Central African Republic is now fully secured," Colonel Sani Usman said in a statement.
Al Jazeera and Reuters