At least seven people have been killed by a female suicide bomber who blew herself up at a crowded market in northeast Nigeria, according to witnesses and officials.

The mid-afternoon attack on Thursday in Biu, 180km south of the Borno state capital Maiduguri, is the latest in a spate of similar attacks in the region.

This was the first bombing in the area, which came before a visit by the former governor to Biu, according to a witness who is a member of the Civilian Joint Task Force (JTF).

Biu is the biggest town in southern Borno, and Boko Haram fighters have made repeated attempts to bomb the market, which is open on Mondays and Thursdays.

The JTF was formed by residents to combat Boko Haram, the Nigerian armed group.

Boko Haram has been blamed for using women and young girls as human bombs as part of its deadly campaign to create an Islamic state in the country's far northeast.

A senior security source in Maiduguri confirmed the deadly suicide blast but had no immediate details on casualties.

But multiple witnesses and a nurse at the Biu general hospital said that at least seven people were killed by the explosion.

Boko Haram suspected

Boko Haram was suspected in the attack, said the JTF member who spoke on condition of anonymity because he was not permitted to speak to the press.

He said they are evacuating the dead and the injured.

Boko Haram also bombed a police station in northeast Nigeria on Thursday, as the fighters pressed on with attacks despite a multinational offensive targeting their strongholds, witnesses and security sources said.

Separately, another attempted suicide attack was foiled outside a political office elsewhere in the northeast, raising fears of growing unrest in the run-up to Nigeria's general election, which has been postponed by six weeks.

Last month, scores of fighters tried to raid Biu but were pushed back by the military.

In November last year there were claims that civilian vigilantes put the heads of slain Boko Haram fighters on wooden spikes and drove them around the town.

Source: Agencies