Pirates Attack Ship Off Nigeria, Kidnap Four

Pirates in speedboats attacked an oil supply vessel and kidnapped four Indian and Polish crew members in increasingly dangerous waters off Nigeria's coast last week, two security sources said on Wednesday.

The gunmen launched their assault on the Singapore-flagged tugboat MDPL Continental One around 30 nautical miles from land on June 13, the security sources said.

The vessel was ransacked and four crew were taken hostage off the coast of the oil-producing Niger Delta, one of the sources told Reuters.

The boat's management company CS Offshore told Reuters there had been an incident that day but declined to go into further details "in order not to endanger those involved".

Pirate attacks off West Africa's mineral-rich Gulf of Guinea have almost doubled from last year and threaten to jeopardise the shipping of commodities from the region. They have already jacked up insurance costs.

The attacks are mostly carried out by armed Nigerian gangs also blamed for kidnappings and oil theft on land.

Reporting by Joe Brock; Editing by Tim Cocks and Andrew Heavens (C) Reuters 2013.