A female suicide bomber has killed at least seven people at a crowded bus station in north-eastern Nigeria.

Police say more than 30 others were wounded in the city of Damaturu, capital of Yobe State.

No group has said it carried out the bombing but the jihadist group Boko Haram has previously launched attacks in the city.

On Saturday, Boko Haram fighters tried to take over the regional capital of neighbouring Gombe state.

They were repelled by Nigerian troops backed by a fighter jet.

Marcos Danladi, police commissioner of Yobe State, said Sunday's attack took place at the Damaturu Central Motor Park.

According to reports, the female suicide bomber arrived in a vehicle and walked into a crowd outside a grocery store at the end of the terminal where she detonated her explosives.

Witness Adamu Muhammad said the bus station "descended into panic".

A shop owner told AFP news agency that an angry mob stopped emergency workers from retrieving the remains of the bomber and instead set them on fire.

Thousands of people have been killed and more than three million displaced by Boko Haram's insurgency.

The Islamist militants, who are fighting to create an Islamic state in north-eastern Nigeria, have become a regional threat.

In response, Nigeria, Niger, Chad and Cameroon have agreed to form a regional military force to combat the group.

Growing insecurity in the north-east led Nigeria to postpone elections due to be held on 14 February.

Correspondents say the insurgency has also cast doubt on the leadership of President Goodluck Jonathan, who is accused of not having done enough to contain it.