Two Italian priests and a Canadian nun were kidnapped in Cameroon months after a French priest was seized nearby.

The priests were named as Giampaolo Marta and Gianantonio Allegri, missionaries who had been working on improving water supplies and fighting the spread of HIV Aids, and the nun as Gilberte Bissiere.

It is not clear who took them, though Nigerian Islamist sect Boko Haram operates in the area, in the north of the African country.

A government source said armed forces were trying to free the hostages, without going into detail.