The soldiers were driving along the Kolofata-Amchide road in the region when their vehicle hit a mine, a security official in the region told Xinhua.

"It is a sad incident. They are undergoing treatment. Two of them are in critical conditions," said the official, who asked not to be named.

It was not immediately clear who was responsible. The Boko Haram extremist group is active in the region and has carried out deadly raids against civilians and soldiers.