The Chad government announced in a statement that "some soldiers" from the Chadian contingent based in Tera had been arrested and "will suffer the appropriate sanctions".

Niger's anti-jihadist strategy is being strengthened by 1,200 Chadian troops, under the banner of the five-nation G5 Sahel group.

"There was a young girl, aged 11, and two married women aged 23 and 32, one of whom is now pregnant, who were raped. Five other woman escaped being raped," CNDH rapporteur Hamidou Talibi told AFP.

"There is another category of women who were raped but don't want to testify as they would be stigmatised (in their communities)," said Talibi.

"It was soldiers from the Chadian contingent who carried out the rapes," he added, without identifying any culprits.

Tera is a town in the Tillaberi region which is close to Burkina Faso and Mali in an area prone to attacks by jihadist groups.

The G5-Sahel force in a statement spoke of "three confirmed rapes" as well as attempted rapes involving Chadian soldiers.

The five-nation force, which also involves troops from Niger, Burkina Faso, Mali and Mauritania, denounced "facts of such gravity", adding that those implicated had been repatriated and a criminal investigation opened by Niger and Chad.