Tanks, rocket-propelled grenades and assault rifles were deployed in a battle for battle for control of grazing land and water for livestock.

The clash between members of the Sa'ad and Suleman factions of the Habar Gidir clan broke out on Wednesday afternoon over control of several small towns in the arid Mudug and Galgudud regions of Somalia, according to a militia commander and an aid worker who were present during the fighting.

The two sides have fought several times for control of the region. It was not immediately clear what sparked the latest conflict. Each side has accused the other of attacking positions occupied by its fighters. Residents say the militia have been building up to conflict for several weeks.

The militia commander and aid worker said at least 15 combatants were killed. At least another 35 people were wounded, the commander said on the condition of anonymity.

Somalia has had no effective central government since opposition leaders ousted Mohamed Siad Barre, the former dictator, in 1991. They then turned on each other and seven million strong country now comprises an anarchic patchwork of battling fiefdoms ruled by heavily armed militias.