FRANCE says more than 20 Islamist rebels were killed in an operation in northern Mali that resulted in the death of a French soldier.

The French military's general staff said in a statement on Tuesday that 150 French and Malian soldiers took part in the operation launched on Monday that "was able to locate terrorists in their sanctuary, pursue and neutralise more than 20 of them".

It identified the dead soldier as Staff Sergeant Harold Vormezeele, an NCO and commando with the 2nd Foreign Parachute Regiment, an elite unit of the French Foreign Legion.

He was the second French soldier killed since the start of France's military intervention in Mali on January 11.

The defence ministry said he was killed around 11am on Tuesday.

"French forces consisting of a unit of paratroopers, backed by forward air control and an armoured patrol, were attacked by a group of terrorists while on a reconnaissance mission in the Adrar massif about 50 kilometres south of Tessalit," it said.

It said two Mirage fighter jets were called in and destroyed two heavy machinegun nests from where the attacks were carried out.

President Francois Hollande offered condolences to the soldier's family, saying in a statement that he "salutes the courage and sacrifice of our soldiers involved in the fight against terrorist movements alongside Mali's armed forces and African troops."

Originally published as More than 20 Islamists killed in Mali