At least 19 people have been killed and several injured by a bomb strapped to a girl reported to be aged about 10 in north-eastern Nigeria, police say.
The bomb exploded in a market in the city of Maiduguri, in Borno state.
"The explosive devices were wrapped around her body," a police source told Reuters.
No group has said it carried out the attack. The market is reported to have been targeted twice in a week by female bombers late last year.
Correspondents say that all the signs point to the militant Islamist Boko Haram group.
They have been fighting to establish an Islamic caliphate in the north-eastern states of Borno, Yobe and Adamawa, which have borne the worst violence in their five year insurgency.
Borno State police spokesman Gideon Jubrin said that the girl bomber let off an improvised explosive device near the area of the Maiduguri market where chickens were sold.
The BBC's Abdulahi Kaura in Lagos says that this will not be the first suicide bombing involving young girls, part of a new militant strategy intended to capitalise on the fact that people in the Muslim-dominated north are less suspicious of women.
In other violence reported on Saturday a vehicle in Yobe state exploded at a checkpoint near a police station, killing at least two people.
The blast follows heavy fighting in the Yobe state capital Damaturu on Friday night, with buildings destroyed and civilian casualties reported.
Hundreds of people were killed on Wednesday in an assault by Boko Haram on the town of Baga, following on their seizure of a key military base there on 3 January,
Scores of bodies from that attack - described by Amnesty International as possibly the "deadliest massacre" in the history of Boko Haram - are reported to remain strewn in the bush.
District head Baba Abba Hassan said most victims in the Baga attack were children, women or elderly people who were not able to escape when insurgents forced their way into the town by firing rocket-propelled grenades and assault rifles.
Boko Haram has taken control of many towns and villages in north-eastern Nigeria over the past year.
The conflict has displaced at least 1.5 million people, while more than 2,000 were killed last year.
Boko Haram at a glance
- Founded in 2002
- Initially focused on opposing Western education - Boko Haram means "Western education is forbidden" in the Hausa language
- Launched military operations in 2009 to create an Islamic state
- Thousands killed, mostly in north-eastern Nigeria - also attacked police and UN headquarters in capital, Abuja
- Some three million people affected
- Declared terrorist group by US in 2013
Some 10,000 people have fled to Chad over the last week to escape the violence, raising fears of a humanitarian crisis, officials say.
Others are fleeing to Maiduguri, the capital of Borno, in buses provided by the government.