There has been an explosion at a church inside a military barracks in Kaduna state in northern Nigeria, military sources have said, according to BBC News.

Unconfirmed reports say the blast came after a car was driven into the barracks in Jaji and explosives in it detonated.

It is not clear whether there were casualties or who was responsible.

However, several churches in the state have been attacked in recent months by the Islamist militant group Boko Haram.The group is fighting to overthrow the government and impose an extreme form of Sharia law.

At least 50 people were killed in bombings in Kaduna in June and the reprisals that followed.And almost a month ago seven people died in a suicide bombing at a Roman Catholic church in the state.

Kaduna is on the dividing line between Nigeria's mainly Christian south and the north, which has a large Muslim majority.