The fighting took place in a desert area between the towns of Gao and Kidal.

There are conflicting reports about the numbers of people killed or injured.

The French news agency AFP quoted a military source in the Malian capital, Bamako, as saying that at least 30 people had been killed, but a senior provincial official in Gao, Mr Chaka Sisse, said three people had been killed and 17 others injured.

Clashes 'a surprise'

AFP said that the violence lasted six hours and stemmed from a dispute over leadership and division of territory in the area.

Mr Sisse said that the clashes came as a surprise, since the communities signed a peace accord in July.

Mali has a reputation as one of Africa's least ethnically riven nations and its local traditional leaders are famed for their ability to mediate and resolve conflicts.

But competition for shrinking natural resources, the increased availability of small arms and the unreliablity of seasonal rains have created tensions which sometimes spill over into violence.