France says its air force - working with the army in Chad - has carried out airstrikes against an armed group which had crossed the border from Libya.

A statement by the French military said a fighter jet took off from the capital, N'Djamena, and targeted a column of 40 vehicles with two airstrikes.

Last year, a fledgling rebel movement seeking to topple the Chadian president, Idriss Deby, carried out attacks in the north of the country.

The Command Council for the Salvation of the Republic first attacked last August.

Chad has also been under threat from Islamist militant factions.

France is supporting a regional force, known as G5, fighting the jihadists across the Sahel region.