At least 50 people have been killed in five days of fighting in central Somalia, according to reports.
People have been forced to flee as homes are destroyed
Another 130 people are said to have been injured in the clashes in the Galgudud and Mudug provinces near the Somali border with Ethiopia.
The land dispute broke out last week between rival sub-clans.
The new Somali cabinet, which is based in neighbouring Kenya, has appealed to both sides to stop fighting and begin peace talks.
The fighting broke out between two divisions of the same clan on Wednesday, in the village of Gelinsor near the Ethiopian border, and spread to villages near the Indian Ocean.
Homes blown apart
Revenge killings were fuelling the violence, residents said.
The BBC's correspondent Mohamed Olad Hassan said about 500 militiamen were thought to be fighting each other, using anti-tank weapons and heavy machine guns mounted on pick-up trucks.
There were reports of anti-aircraft guns being fired horizontally, wiping out people's mud homes.
Many people are said to have fled the fighting. The injured include women and children.
What started the fighting is unclear, though the two wings of the Habr Gedir sub-clan of the Hawiye clan have a recent history of clashes over pastoral land and water wells.
Our correspondent says efforts by tribal elders to mediate have so far failed, with some of them being killed.
Somalia has been without a government since dictator Mohamed Siad Barre was ousted in 1991.
A new administration has been formed in neighbouring Kenya and aims to establish itself in the country in the coming months.