At least five policemen were killed in an attack by armed men in Nigeria's southeastern Imo state, a police spokesman said on Tuesday, the latest incident in a state rife with gang and separatist violence.

Armed groups have attacked police stations and government buildings in states in Nigeria's southeast, which authorities often blame on the proscribed separatist Indigenous People of Biafra (IPOB) group. IPOB denies the charges.

Imo police spokesman Henry Okoye confirmed the attack occurred at Ehime Mbano local government area of the state, but did not immediately provide details because investigations are ongoing.

Local media reported at least eight fatalities including soldiers and men of Nigeria's Civil Defence Corps, a paramilitary agency.

Widespread insecurity has rocked Nigeria, Africa's most populous nation, with armed attacks and kidnappings in the northwest, a festering Islamist insurgency in the northeast and violent sectarian and herder-farmer clashes in the central region.

IPOB has been campaigning for southeastern Nigeria, the homeland of the Igbo ethnic group, to be an independent country.

More than a million people died, mostly of starvation, during a three-year civil that began in 1967 when the region attempted to secede under the name Republic of Biafra.

Reuters