France said its nationals were at risk of kidnappings or attacks in the West African state of Benin, warning of a specific danger close to neighboring Niger.

The advisory came after a French family of seven, including four children, were abducted by suspected Islamist militants in Cameroon on Tuesday, the first case of foreigners being seized in the mostly Muslim north of the country.

It highlighted the threat to French interests in West Africa since Paris deployed thousands of troops to Mali to oust al Qaeda-linked Islamists who controlled the country's north, Reuters reports.

"Despite the Benin authorities committing to increase security in particular areas, the risk of kidnappings and attacks exists in Benin," the foreign ministry said in an updated travel advisory on its website.

It warned its 3,700 citizens in Benin to avoid going out at night and against all travel on the main road leading from Tchaourou, about 350 kilometers north of the capital Porto-Novo, to Malanville and the W National Park on the border with Niger.

The United States and African governments are backing the six-week-old campaign against militants in Mali, where Benin has also sent troops to join an African force being deployed.

Islamists have threatened to strike back at anyone who supports the mission.

The kidnapping in Cameroon brought to 15 the number of French citizens being held in West Africa.

Security forces are searching for the family who were taken into Nigeria, local police said on Friday.

French President Francois Hollande said on Saturday there was no new information on the whereabouts of the hostages.