Port Harcourt: Five officers were killed when unknown gunmen attacked a police station in Nigeria’s unstable southern oil region on Sunday.

A rivers State police spokeswoman said the assailants stormed a station on Bonny Island, a major crude oil export terminal, and stole seven weapons early on Sunday.

The cause for the attack is not clear.

Nigeria, Africa's biggest petroleum producer, has suffered from increasing conflict in Its southern oil region as criminals and militants vie for illegal profits linked to the oil industry.