A SUICIDE bomber has driven a car full of explosives into a church in northern Nigeria, killing 12 people.

It was not clear who was responsible for the attack, although churches have been targeted this year by militant Islamist group Boko Haram, which has increasingly used suicide bombers.

Security forces at a road block nearby said the bomber forced his car through the checkpoint and drove into the church in Yelwa, on the outskirts of the city of Bauchi.

"I had just left after the morning service and was out of the church when I heard a loud explosion. I rushed back and there were dozens of people lying in pools of blood," said Aliku Jon, a mechanic. "Many were injured including two police officers."

Boko Haram, which says it is fighting to reinstate an ancient Islamic caliphate in northern Nigeria that would impose stricter sharia law, has been blamed for hundreds of killings over the past two years.

It has become the number one security threat in Nigeria, Africa's top oil producer, and has linked up with other Islamist groups in the region such as al Qaeda's north African wing.

The sect had been less active in recent weeks, as a security crackdown in the north led to the deaths and arrests of several commanders.