Gunmen attacked a security vessel off the coast of Nigeria on Thursday in an oilfield operated by Canada's Addax Petroleum, the latest in a series of attacks on the country's deepwater oil industry.
Two private security sources working in the oil sector said a gang in two boats attacked the vessel at around 3am (0200 GMT) off the coast of southern Nigeria's Akwa Ibom state.
One source said the captain of the vessel, a retired army major, had been killed and another crew member wounded. There was no independent confirmation of this.
The attack took place in OML 123, a 370 sq-km licence area operated by Addax. Several similar attacks took place in the area last year and there have been at least 10 such raids in the wider Niger Delta offshore region since the start of January.
Some industry executives say if the rise in piracy is not checked, smaller oil services firms which are vital to the smooth operations of the offshore industry may consider withdrawing.
"If they pull out, it will cripple the industry," one industry source said.
The Niger Delta has long been plagued by insecurity, particularly since militants saying that they are fighting for a fairer share of the region's natural resources began blowing up oil pipelines and kidnapping expatriate workers three years ago.
But the offshore industry, on which Nigeria is depending to raise output from around 2 million barrels per day (bpd), had been considered relatively immune from the unrest because of the long distance such operations are located from land.