Survivors say 44 people have died of thirst after their truck broke down in the Sahara Desert in northern Niger, the BBC reports, quoting the Red Cross.
The six survivors, all women, walked to a remote village and are being looked after in Dirkou, Niger, Red Cross official Lawal Taher said.
They say several children are among the dead.
So far no-one has visited the site to identify the bodies, Mr Taher added.
The route from Niger to Libya is one of the main ways migrants reach North Africa before crossing the Mediterranean Sea to get to Europe.