Fresh fighting broke out on Tuesday between the Fallata people and an Arab tribe in villages outside Nyala, the capital of South Darfur state, witnesses said.

"The fighting has continued until Thursday, and has so far killed some 30 people and wounded dozens," a leader from the Fallata said, requesting anonymity.

One resident of South Darfur, Mohamed al-Fatteh, said fighting erupted after an Arab leader was killed.

A leader from an Arab group also said that the fighting continued on Thursday, reporting that there were "multiple killings and wounded."

Sudan's western restive Darfur region was ravaged by a bitter a civil war that erupted in 2003.

The conflict pitted ethnic minority rebels who complained of discrimination against the Arab-dominated government of then-president Omar al-Bashir.

Khartoum responded by unleashing the Janjaweed, mainly recruited from Arab pastoralist tribes, who were blamed for atrocities including murder, rape, looting and burning villages.

The scorched-earth campaign left 300,000 people dead and displaced 2.5 million, according to the United Nations.

The main conflict has subsided over the years, but the region remains awash with weapons and deadly clashes often erupt over access to pasture or water.

Earlier this month, separate clashes broke out among herders and farmers in the rugged mountainous region of Jebel Moon in West Darfur, leaving at least 35 people killed.

Scores of people have been killed and hundreds of houses torched in several bouts of violence in Jebel Moon, as well as elsewhere in Darfur in recent months, the United Nations and medics say.

The violence has reflected a broader security breakdown in Darfur following last year's military takeover led by army chief Abdel Fattah al-Burhan, that derailed a transition to full civilian rule.