Lagos, April 27 (IANS) At least five policemen were killed after gunmen attacked a police station in southern Nigeria's Imo state, local police said.

A gun battle erupted after unidentified attackers broke into the police station and freed some inmates. "Five officers have been killed, while one is yet to be accounted for," said Orlando Ikeokwu, an Imo police spokesperson, in a statement.

Earlier this month, the state saw a major attack on security formations, the Xinhua news agency reported.

On April 5, armed men attacked the headquarters of the Imo state police command and a correctional facility in Owerri, capital city of the state, and freed over 1,800 inmates.

--IANS int/rs