At least 11 people have been killed in ongoing clashes between Arab and non-Arab groups in Sudan's restive Darfur region, a doctor said Saturday.

Violence erupted on Wednesday around 20 kilometres (12 miles) from the South Darfur state capital Nyala pitting Arab herders against farmers from the Daju minority and other non-Arab ethnic groups, witnesses said.

It was not immediately clear what sparked the fighting which has shown no signs of abating.

"The number of bodies that have arrived at the hospital has reached 11," the doctor at Nyala hospital told AFP, adding at least 20 people were treated for gunshot wounds.

Adam Regal, spokesman for the General Coordination for Refugees and Displaced in Darfur, said the death toll was "likely to be much higher as the fighting is still ongoing".

The official news agency SUNA had earlier said seven people were killed and that security forces had been sent to the area to quell the violence.

"A group of herders riding camels and vehicles attacked the village of Amuri on Friday, leaving the site burnt and four people killed," SUNA said, adding that two people had been killed between Wednesday and Thursday.

Another person was killed when the fighting spread to nearby villages, which were "partially burnt" as shops were looted, the news agency added, quoting a government statement.

Hundreds of people protested against the violence outside a government building in Nyala, according to witnesses.

Ethnic clashes often break out in Darfur, a vast region the size of France which was ravaged by a bitter civil war that erupted in 2003.

That conflict pitted ethnic minority rebels against the Arab-dominated government of then-president Omar al-Bashir.

Some 300,000 people were killed and 2.5 million displaced, according to the United Nations.

While the conflict has subsided over the years, violence still flares between nomadic herders and settled farmers over access to scarce water and grazing land.

Sudan is still grappling with the crippling aftermath of a military coup led by army chief Abdel Fattah al-Burhan in October last year.

Civilian groups signed a preliminary deal with the military to end the crisis earlier this month but it has been criticised as "opaque".

Conflicts in Sudan's far-flung regions have killed around 900 people this year and driven almost 300,000 from their homes, according to a report this month by the United Nations Office for the Coordination of Humanitarian Affairs.