Another explosion near a church has killed four children in Nigeria's northeastern state of Borno on Thursday, a region which has been beset by attacks by a radical Islamist sect, police said.

The blast in the town of Damboa, around 90 km (56 miles) south of the state capital Maiduguri, came just hours after a suspected suicide bomber detonated explosives outside the national police headquarters in the capital Abuja.

"The children were playing in a compound near the church when the blast went off, killing the four and wounding another," Borno state police commissioner Jinjiri Abubakar told Reuters, adding that the blast appeared to have been caused by a bomb.

Police also said the group was believed to have been responsible for the attack on their headquarters in Abuja on Thursday, which killed several people.�