A number of Boko Haram members are believed to have trained with al-Qaida militants in the Islamic Maghreb in northern Mali.

France's Defense Minister Jean-Yves Le Drian said on Wednesday that there was no proven link between the French operation in Mali and the kidnapping. But speaking on France-2 television, he said, "These are groups who adhere to the same fundamentalism and who have the same methods, whether it is in Mali, in Somalia or in Nigeria, who want to create a lawless zone" stretching from the Atlantic across the southern edge of the Sahara to Sudan.

On Tuesday, the French embassy in Yaounde advised all French nationals in Cameroon's northern border areas to stay indoors.

Though it is the first abduction of Western tourists on Cameroonian soil, there have been several hostage-takings off the coast attributed to pirates, and in neighboring Nigeria.

In December, French engineer Francis Collomp was kidnapped in Nigeria in an act claimed by Nigerian radical Islamist group Ansaru, which is thought to be a Boko Haram splinter group.

On Monday, Ansaru also claimed the kidnapping of seven foreigners in a deadly weekend raid on a construction site in northern Nigeria.

Claiming responsibility for that attack, Ansaru invoked "the transgressions and atrocities committed by European nations in several places, including Afghanistan and Mali", singling out France in particular.

Tuesday's abduction brings the number of French hostages abroad to 15 - all in Africa, with at least six being held by AQIM.

AFP-AP