In a statement on Monday, the military said that Mirage 2000 fighters intervened "together with the Chadian army" to "halt the hostile advance and disperse the column," which had crossed deep into Chadian territory.

The warplanes are based near N'Djamena, the Chadian capital, as part of France's Barkhane counter-terrorism force in the Sahel.

"The column had been spotted at least 48 hours beforehand," armed forces spokesman Patrik Steiger told AFP.

The Chadian airforce carried out strikes to try to repel it before asking the French to intervene, he said.

On Sunday morning, French planes made low warning passes over the column but it continued to advance, triggering a decision to scramble more fighters, which carried out two strikes at around 6 p.m. Paris time.

Steiger said the group had crossed 400 kilometres (250 miles) of Chadian territory before being halted "between Tibesti and Ennedi" in the northwest.

He did not identify which armed group they belonged to.

The Chadian military has carried out several air strikes recently in the arid north against Libya-based rebels.

It also launched an operation last year aimed at "clearing out" illegal gold miners whose arrival in the far north has fomented unrest with locals.