Three French nationals were seized after pirates boarded an oil industry supply vessel off the coast of Nigeria.
The abduction comes just six days after seven people, including five French nationals, working in neighbouring Niger's uranium fields for French nuclear giant Areva were kidnapped by Al-Qaeda in the Islamic Maghreb.
The men's employer in Nigeria, French maritime services firm Bourbon, and the French foreign ministry said they had contacted the kidnapped workers' families and were working with Nigerian authorities to secure their release.
Bourbon has also set up a crisis cell in the French town of Marseille.
French Defence Minister Hervé Morin played down speculation that the hostage-takers may have had a political motive. In a FRANCE 24 interview on Wednesday Morin said that "everything points to it being a classic act of piracy."
Bourbon said in an online statement that its boat had been working on an off-shore field owned by Addax Petroleum, a Swiss-based subsidiary of the Chinese energy and chemical giant Sinopec.
"The 13 other crew members have remained on board and nobody has been injured. No claim has been made at this stage," Bourbon said.
Addax has several offshore and onshore fields in Nigeria, but its main offshore wells lie in OML123, an oil production bloc 60 kilometres (37 miles) south of the city of Calabar at the far eastern edge of the Niger Delta.
The Gulf of Guinea, south of Nigeria, is one of the world's most notorious pirate hunting grounds, and ships working in the region's huge oil industry are often targeted by kidnap and ransom gangs.
Bourbon has been the target of several attacks in the past two years in the Niger Delta oil-producing area.
Nine Bourbon workers were taken hostage along with their ship in January last year and freed a few days later. In October 2008 another of its ships was seized by pirates off the Nigerian coast.
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