Gunmen have killed a police inspector in southeast Nigeria, police said on Monday, the latest attack in the restive region where dozens of officers have died this year.

In the attack on Sunday, gunmen ambushed a police patrol in the commercial town of Onitsha in Anambra state and opened fire, state police spokesman Ikenga Tochukwu said in a statement.

- The attackers drove in a Sienna vehicle... and started shooting at the patrol vehicle along Ukegbu junction - he said.

- Unfortunately, during the exchange of gunfire, one police inspector paid the supreme price.-

Other officers were wounded in the attack, he said.

No group has claimed responsibility for recent attacks, but police often blame the Indigenous People of Biafra (IPOB), a proscribed separatist group demanding an independent state for the ethnic Igbo people.

IPOB denies its armed wing, Eastern Security Network, is involved in the attacks, but separatist agitation is on the rise in southeast and southwest Nigeria.

Tochukwu said that "in a bid to escape the police responding team, the hoodlums set the patrol vehicle ablaze."

In nearby Enugu state, gunmen also attacked an electoral office and set parts of the building on fire.

Officials however said the blaze was put out before vital election materials and equipment could be damaged.

Dozens of police officers and other security personnel have been killed since the beginning of the year in targeted attacks in the southeast.

Prisons have also been raided with scores of inmates freed and weapons carted away.

IPOB's leader Nnamdi Kanu is in government custody since he was arrested abroad in June and brought back to Nigeria to face treason charges.

Separatist activism is especially sensitive in southeast Nigeria, where a declaration of an independent Republic of Biafra by Igbo army officers 50 years ago sparked a civil war that left more than one million people dead.