Seven French tourists from one family, including four children, were kidnapped Tuesday in northern Cameroon, French President Francois Hollande said.
He was informed that the tourists were seized by a Nigerian "terrorist group that we know well", Hollande told reporters while on a visit to Athens.
"What is most probable is they will be taken to Nigeria," he said, adding France was doing everything possible to prevent that outcome.
A source close to the French embassy in Yaounde had earlier said that unidentified men, apparently on motorbikes, had captured the seven tourists in the locality of Dabanga near the Nigeria border.
"Clearly the tourists were returning from the Waza natural park," the source said.
An anonymous source in the park said the tourists visited it on Monday. "They slept in the park's tourist camp where they left this morning," the source said.
A security source in the area told AFP that security forces were hunting for the kidnappers the length of the border with Nigeria.
It's the first time that Western tourists have been kidnapped in Cameroon, although hostage taking frequently occurs off the Cameroonian coast, the last incident dating back to February 8.
In December, French engineer Francis Collomp was kidnapped in Nigeria in an act claimed by the Nigerian radical Islamist group Ansaru.