Video and images shared on Twitter show several uniformed men with French military insignia crouching on the ground guarded by a group of Chadian soldiers, one of whom is speaking on the phone. Some posts refer to the men being “arrested” because they were illegally mining gold or spying.

The joint staff of the French armed forces told the BBC that the incident - on 8 June - was a “misunderstanding”.

They said a joint French-Chadian patrol had set off from Abeche in eastern Chad and was about 30 miles (48km) away from the border, when they were stopped at a Chadian army checkpoint, which had been unaware of their mission.

The French soldiers were out checking the state of the roads before the rainy season in Chad, and were allowed to proceed once the misunderstanding had been cleared up, the French authorities said.