Fresh fighting between feuding Arab tribes in Sudan's Darfur region has killed 11 people, tribal leaders said on Tuesday, adding to worsening violence in the region.

The Gimir and Beni Halba tribes have been clashing over land ownership since at least April, around Edd al-Fursan about 100 kilometres (60 miles) southwest of the South Darfur state capital Nyala.

Abaker al-Toum, a Gimir chief, told AFP the Beni Halba attacked three Gimir villages on Monday.

"They came on vehicles, motorcycles, horses and camels, with heavy weapons," he said.

"We lost five martyrs," and some houses were burned to the ground, he said.

A Beni Halba leader, who declined to be named, confirmed fighting resumed in three areas.

"We lost six of our men," he said in brief comments. "We are fighting to protect our land."

An upsurge in inter-tribal and inter-ethnic fighting "has been the major source of violence, fatalities and displacement of civilian population" in Darfur this year, the head of the African Union-UN peacekeeping mission (UNAMID), Mohamed Ibn Chambas, told AFP last week.

In early May at least 80 people died in battles between the Beni Halba and Gimir.

"In all these incidents the government didn't shoot one bullet against these attackers," Toum said.

UN experts, human rights activists and tribal leaders have accused government security forces of involvement in Darfur's tribal fighting.

But Chambas said it is hard to tell who is on which side as police and militia also have ethnic or tribal affiliations

In late May, an AFP photographer found the bodies of several victims killed in fighting between the Gimir and Beni Halba.

Across Darfur, tribal clashes and fighting between government and rebel forces have forced an estimated 300,000 people to flee their homes already this year, the United Nations says.

There were already 1.4 million people living in camps after fleeing their homes in the face of the decade-long conflict, which began when ethnic minority rebels rose up against the Arab-dominated Khartoum government.

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