A bomb explosion in a market in the northeastern Nigerian city of Maiduguri on Saturday killed at least 16 people and injured more than 20, a security source and witnesses said.
Maiduguri, the capital of Borno state, is often bombed as it lies in the heartland of an insurgency by Sunni Muslim militants Boko Haram to revive a medieval caliphate in Africa's most populous country, also the continent's biggest energy producer.
A Nigerian security source said at least 11 people were killed and 24 injured by a bomb that went off at 12:15 p.m. (1115 GMT). There were at least 16 bodies of bomb victims counted in one hospital by mid-afternoon, civilian joint task force member Zakariya Mohammed told Reuters .
"Right now, there are 27 injured people in Borno Medical Hospital while more were taken to other hospitals," he said.
Borno, Yobe and Adamawa states in Nigeria's northeast are worst affected by the Boko Haram five-year-old insurgency. Last year more than 10,000 people died in the bloodshed.
About 130 km away in the Yobe state capital Damaturu, the army managed to repel an Islamist militant attack on Friday evening, a Reuters reporter in the city and witnesses said.
The Reuters witness said he saw a number of buildings had been burnt down in the violence, including the police area command station and a mosque in the Abacha market, along with several shops.
No casualty figure was immediately available and the militants took their dead away with them. Damaturu was last attacked in early December when air strikes were required to repel advancing militants.
Boko Haram's revolt is seen as the gravest security threat to the country of 170 million people and a headache for President Goodluck Jonathan ahead of an election on February 14.