In December, two Canadian diplomats disappeared in Niger. They are presumed to have been kidnapped and have not been heard from. The government has accused Tuareg fighters of committing that attack.

Tuareg base attacked

Separately on Thursday, 31 Tuareg fighters were killed when the Malian army attacked a base at Kidal, around 200km to the north of Menaka, Mali's defence ministry said.

The base was allegedly under the command of Ibrahima Bahanga, whose group Malian authorities accuse of attacking army posts and trying to control smuggling routes in the Sahara.

Tuareg - a nomadic desert people - groups have been fighting the army in northern Mali this year and have undertaken uprisings in Niger and Mali in past years in an attempt to gain autonomy for their traditional homeland.

Up to 1.5 million Tuareg are said to live across parts of Algeria, Burkina Faso, Libya, Niger and Mali. About 700,000 Tuaregs live in Niger and 300,000 in Mali.