France authenticated an Al-Qaeda claim to have kidnapped five of its nationals together with a Togolese and a Madagascan in Niger last Thursday, as it awaited the kidnappers' demands.

"We have not received proof of life, but we have good reasons to believe the hostages are alive," French foreign ministry spokesman Romain Nadal said after Al-Qaeda in the Islamic Maghreb (AQIM) claimed responsibility.

...Foreign Minister Bernard Kouchner said France and its partners would continue to "be as careful as possible" and lend all their resources to the release of the hostages.

Speaking on the fringes of a UN summit in New York, he said he was "not really surprised that Al-Qaeda is behind this kidnapping.

"Now that this is a certainty, we will continue -- the French, our allies, the countries of the Sahel and Europe I hope ... to put all the means at our disposal for their liberation," he added.

Pirates boarded an oil industry supply vessel off Nigeria on Wednesday and seized three French seamen, in the second hostage drama for French energy workers in West Africa in less than a week.

The men's employer, 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.

A spokesman for the Nigerian military taskforce deployed to protect the west African giants's oil industry confirmed the attack, but said that in total four hostages were taken.

Wednesday's drama came just six days after five French nationals working in neighbouring Niger's uranium fields were kidnapped by Al-Qaeda militants, in an unrelated attack that has already stretched French assets in the region.