A suicide bomber in the Nigerian city of Damaturu has killed at least six soldiers and two civilians, police say.

According to an eyewitness, the bomber rammed a car into a military vehicle that was part of a convoy.

The attacker's vehicle was being chased by troops when the bomb went off, a police spokesman said.

No group has said it carried out the bombing, but Damaturu is the capital of Yobe state which has seen frequent attacks by Islamist sect Boko Haram.

Army victims
 
"The lone suicide bomber detonated the bomb before the car he was in could be stopped, killing the six soldiers and one civilian," state police chief Patrick Egbuniwe told the Reuters news agency.

"Another civilian died of his wounds in hospital shortly after." He said that nine soldiers were in hospital receiving treatment for their wounds.

Damaturu is 130km (80 miles) west of Maiduguri, the Boko Haram stronghold.

The group wants Islamic law, or Sharia, to be imposed across Nigeria - and has carried out a series of deadly attacks in the past two years.

Boko Haram means "Western education is forbidden".

Sunday's blast follows a failed attempt to blow up the state's most senior Muslim cleric, the emir of Fika, on Friday.

The bomber tried to drive a car into the emir's convoy just after he had left Friday prayers. He missed his target but several people in the area were badly injured.