Benin's military says that militants inflicted heavy losses on the country's armed forces during an attack this week on a fortified military post in the north.

Benin's armed forces have suffered heavy losses in an attack on one of their most well-equipped positions in the north, where troops are trying to curb cross-border assaults by Islamist militants, the national guard's chief of staff said on Thursday.

Twenty-eight soldiers were killed in an attack in northern Benin, a security source told AFP on Thursday, as violence blamed on jihadists based in neighbouring countries increases.