Mogadishu , Jan. 12, 2006 (AP)- Clan militias used tanks, rocket-propelled grenades and assault rifles to battle for control of grazing land and water for livestock, killing at least 15 fighters in central Somalia , witnesses said on Thursday.

The clash between members of the Sa'ad and Suleman factions of the Habar Gidir clan broke out on Wednesday afternoon about control of several small towns in the arid Mudug and Galgudud regions of anarchic 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 preparing for conflict during the past several weeks.

The militia commander and aid worker said at least 15 combatants were killed. At least 35 people were wounded, the commander said on the condition of anonymity because he was not authorised by colleagues to speak to journalists.

Somalia has had no effective central government since opposition leaders ousted dictator Mohamed Siad Barre in 1991.

They then turned on each other, transforming this nation of seven million into a patchwork of battling fiefdoms ruled by heavily armed militias.