Malian security forces on Wednesday were hunting a group of drug dealers ferrying a tonne of cocaine and hashish through the desert, a Malian army source said.

"We have deployed the necessary troops to track a ton of drugs and the traffickers who have turned part of the Malian desert into a drug market and corridor," said the source, speaking from northern Mali.

He said the drug consignment had led to a dispute between two drug networks, one from the Sahel made up of Mali and Niger traffickers, and one from the Sahara with traffickers linked to the Western Saharan independence movement Polisario Front.

A government source said on Tuesday that four people were killed in the desert between Mali and Algeria in a clash between the rival gangs, who did not agree on how to share the spoils from their haul.

Gangs of drug traffickers, some with ties to the local Al-Qaeda branch, ply their trade in the vast desert through Algeria, Mauritania, Mali and Niger, with drugs passing through camps in Western Sahara, experts say.