The Nato alliance is studying options to offer support to troops fighting against militant jihadists in the Sahel region, UN chief António Guterres has said in a letter reported by the AFP news agency.

He said the move was "the most effective approach to provide sustainable and predictable support to the Joint Force".

The force he was referring to is made up of 5,000 troops in the Sahel drawn from Mali, Mauritania, Niger, Chad and Burkina Faso.

The US has so far rejected the plan that has been supported by France and other African countries, AFP reports.

The UN is calling for more international support for the soldiers in the Sahel region.

Jihadist groups have been staging attacks in the Sahel countries targeting civilians and soldiers.