Mali’s Tuareg rebels clashed overnight with their former Islamist allies, witnesses said yesterday, after the two groups fell out over forming a breakaway state in the northern desert region they control.

The clash involving automatic weapons near the remote regional capital Kidal was the first serious confrontation between the rebel National Liberation Movement of Azawad (MNLA) and the Islamist Ansar Dine.

The two groups are made up of Tuareg tribesmen from rival clans, and the fighting has raised fears of widening chaos in the vast northern swathe of the country, a desert region the size of France.

African leaders on Thursday urged UN backing for military intervention in northern Mali to return the region to central control. The rebel forces faced little resistance from the Malian army when they seized control of the north while a military coup was unfolding in the southern capital Bamako in March.

The rival groups – from the Taghat Melet and Idnane tribes for the MNLA and Ifora for Ansar Dine (Defenders of Faith) – hold separate ideologies and objectives, observers say.

“Divisions are appearing within the armed Tuareg rebel groups,” said Malian journalist Tiegoum Boubeye Maiga. “The crisis is becoming tribal. After having fought the Malian army together... the two groups are now fighting on a tribal basis. It’s very dangerous.”

Calm had returned by dawn yesterday, an official said, but he noted that several MNLA flags had been removed from around the city.

He said three people were injured, but it was not possible to immediately confirm casualty numbers.