Gunmen in speedboats attacked three oil services ships and kidnapped at least two Russians in separate incidents in Nigeria's Niger Delta, private security and industry sources said yesterday.

The Falcon Crest and Falcon Wings were attacked late on Friday off the coast of southern Nigeria's Akwa Ibom state near crude oil facilities operated by Canada's Addax Petroleum.

A Filipino captain on one of the vessels was killed, one security source said. The gunmen were believed to have fled to nearby Cameroonian waters.

No group has claimed responsibility.

Akwa Ibom, which shares a border with Cameroon, has seen an increase in piracy and kidnappings in the past few months.

Nigeria handed over the nearby oil-rich Bakassi peninsula to Cameroon four months ago, angering many Nigerians whose families have since resettled in Akwa Ibom.

Militants in the area have objected to the August 14 transfer, which complied with a World Court ruling.

Friday's attacks took place in the offshore area known as OML 123, referring to the 370 sq-km licence area controlled by Addax. Six similar incidents occurred earlier this year, the most recent two weeks ago, a security source said.

Addax and police officials were not immediately available for comment.

A third ship, operated by Nigerian oil company Monipulo, was attacked by pirates early yesterday near the Abana offshore oilfields, located close to the Nigeria-Cameroon border.

Gunmen in speedboats also attacked a housing compound and kidnapped two Russians working for an aluminium company in the port town of Ikot Abasi in Akwa Ibom early yesterday, security sources said.

The two Russians worked for Nigeria's sole aluminium smelter plant ALSCON, which is owned by the world's largest aluminium producer Russia's United Company RUSAL. The Russian firm confirmed its workers were kidnapped.