Three Nigerien policemen and a gendarme were killed overnight Wednesday when their patrol was ambushed on the border with Algeria, local sources said.

The men were "killed by bandits near Assamaka", a desert town hosting a security post near Niger's northern border with Algeria, a local elected official said.

This account was confirmed by a local news site, Air-Info, and by a security source, who added that the Nigerien army "was pursuing the attackers."

The Niger-Algeria border at Assamaka is notorious for gangs who traffic in drugs, weapons and illegal migrants desperate to cross the Sahara and get to Europe.

Two policemen, a gendarme and a civilian were killed in the same area in 2017, in an attack also attributed to "armed bandits."

The same year, three policemen died when their vehicle, caught in a sand storm, veered off into the desert. Eight survivors were later found after a long search.

Rated the poorest country in the world under the UN's Human Development Index, Niger is also battling jihadist insurgences on its southwestern flank with Mali and on its southeastern border with Nigeria.