PARIS (Reuters) - French and Nigerien troops killed around 15 Islamist militants in a joint air and ground operation in south west Niger on Dec. 27, France’s armed forces and defence ministry said on Sunday.

The air raid and ground assault took place near Tongo Tongo, a village close to the border with Mali and some 175 kilometres (109 miles) north of Niamey.

Tongo Tongo was where, in October 2017, militants killed four U.S. soldiers and four local soldiers in an ambush on their joint patrol.

Islamist militants in Niger are part of a regional insurgency in the poor, sparsely populated deserts of West Africa’s Sahel.

In 2017, five countries - Burkina Faso, Niger, Chad, Mali and Mauritania - backed by France, launched a taskforce, the G5 Sahel, in order to combat the insurgents. France operates in the region through its regional Barkhane force.

During the operation the force recovered 20 motorbikes and a stash of weapons including several machine guns during the operation, the French military said in a statement.