By Tansa Musa

YAOUNDE, Sept 28 (Reuters) - Gunmen in speedboats raided a coastal city in southwest Cameroon early on Sunday, killing one person and robbing four banks, police and state radio said.

It was at least the third sea-borne raid of its kind in less than a year on banks in Gulf of Guinea neighbours of Nigeria, Africa's top oil producer, where the government is fighting a war against Niger Delta militants. The militants often use fast launches to attack oil facilities and army posts.

In December, armed raiders in speedboats stormed two banks in a mainland coastal city of oil-producing Equatorial Guinea, grabbing cash and shooting passers-by. Nigeria's western neighbour Benin has also suffered at least one similar raid.

The raiders on Limbe, described as "suspected pirates" by Cameroon state radio, arrived in six speedboats under cover of darkness, a local police officer told Reuters.

"Residents were awakened from sleep at about 1 a.m. by sustained heavy gunfire that lasted about 30 minutes, followed by sporadic firing into the air for over one hour," said the officer, who asked not to be identified.

The attackers shot dead a hotel driver taking customers to a nightclub.

Using explosives, they blasted their way into four banks in central Limbe, seizing large sums of money. They barricaded roads leading into the town, repelled a group of Cameroonian soldiers and shot at the office of the local prefect.

State radio said Defence Minister Remy Ze Meka visited Limbe to inspect the damage caused by the raiders.

The radio added a sack marked "Port Harcourt Flour Mill Ltd" was left behind in one of the banks.

Port Harcourt is one of the main cities in Nigeria's oil-producing Niger Delta where militants this month stepped up attacks on oil installations and Nigeria's army.

In the past, they have raided ships and rigs far out to sea in the Gulf of Guinea.

Limbe lies on the coast southeast of the oil-rich Bakassi peninsula, of which Nigeria formally handed over control to its eastern neighbour Cameroon in August in line with a 2002 International Court of Justice order.

About 50 people have been killed in border violence in Bakassi in the past year, including attacks on Cameroonian soldiers claimed to have been carried out by a little known group calling itself the Niger Delta Defence and Security Council.

Worried about increased insecurity in the Gulf of Guinea, the navies of the United States and other Western countries have stepped up visits to the region to improve maritime safety, bolster cooperation with local navies and provide training.

The United States imports more than 15 percent of its oil needs from the Gulf of Guinea and this is expected to increase to more than 25 percent by 2015.

(For full Reuters Africa coverage and to have your say on the top issues, visit: http://africa.reuters.com/) (Editing by Pascal Fletcher and Andrew Dobbie)

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