Militants have ambushed a patrol vessel in Nigeria's oil-producing Niger Delta region but the authorities have denied reports that it was hijacked.
A military spokesman said the boat was providing security for oil operations in the Delta when it came under attack, leaving one sailor dead.
Some reports say attackers seized the boat and its crew of eight.
Attacks in the Niger Delta have led to a sharp cut in Nigeria's oil production in recent years.
The boat reportedly belongs to the Canadian Addax Petroleum Corporation.
"Militants and eight naval ratings are on the ship, which left the Calabar area and is heading towards Onne in Rivers state," Nigerian navy spokesman Henry Babalola told the Reuters news agency.
A military official told the BBC that four sailors had been seriously injured, in addition to the one confirmed fatality.
Last month the rebel group, the Movement for the Emancipation of the Niger Delta (Mend) said it attacked an oil pipeline belonging to Royal Dutch Shell in Rivers State.
Attacks on oil installations in the delta have driven up the price of crude oil.
Mend emerged in 2006. They say they are campaigning for a greater share of the region's oil wealth to be kept by local people, but the government says they are criminals motivated by the ransoms they receive from oil companies.
Nigeria is one of Africa's biggest oil producing nations, but frequent pipeline bombings and other attacks by militants have reduced output by an estimated 25%.
The remote and inaccessible creeks of the Delta are home to criminal gangs who seize oil workers for money and attack oil installations.
Piracy in Nigeria's waters has also increased in the last two years, making it one of the most dangerous shipping area in the world.
^ Back to top | BBC Sport Home | BBC Homepage | Contact us | Help | ©
~RS~q~RS~~RS~z~RS~39~RS~)