Three suicide bombers have hit the town of Konduga in Borno State, killing at least 18 people.
Two attacked a fish market and a third struck nearby, security sources said.
Boko Haram jihadists are being blamed for the blasts, though the group has yet to say it was behind them.
Boko Haram has killed some 20,000 people and displaced more than two million since it began a campaign of violence to create an Islamic state in the north of the country in 2009.
The bombers struck on Friday evening in the town, which lies some 30km (18 miles) south-east of the Borno state capital, Maiduguri. Wider reports of the attack only emerged on Saturday.
Some reports speak of 19 dead – 18 civilians and a soldier. At least 50 more were injured.