Paris — France has urged its citizens to leave north Cameroon "as quickly as possible" following the kidnapping of seven of its nationals by gunmen on Tuesday.
French President Francois Hollande said he suspected militant Islamists from neighbouring Nigeria of being behind the abductions.
The abductions came in the middle of a French-led intervention against Islamists in Mali.
Mr Hollande added that the seven tourists, including four children, had probably been taken to northern Nigeria.
Eight French nationals at least are already being held by Islamist groups in Africa.
He added that gunmen from Nigeria's Boko Haram group may have been behind the kidnapping.
The French foreign ministry said on its website citizens were "officially advised not to go to the far north of Cameroon (the shores of Lake Chad in the South Maroua), and the border with Nigeria, until further notice".