Police fired tear gas for a second day on Wednesday at students protesting against the appointment of a new governor in Sudan's war-ravaged Darfur region, witnesses said.
Some were taken to hospital suffering from the gas, they said, estimating that hundreds of people had turned out in Nyala, the capital of South Darfur state, to show support for the former elected governor Abdul Hamid Kasha.
President Omar al-Bashir earlier this month replaced Kasha with an appointee, Hamad Ismail, and broke off parts of South Darfur to add two new states in the region which previously had three.
"People want Kasha," protesters chanted as they marched through the streets, witnesses said.
Many demonstrators were university and high school students, they added.
The unrest began on Tuesday at an official ceremony for the new governor, known locally as a "wali," when protesters threw stones and burned tyres.
Khartoum last year signed a peace deal in Doha with an alliance of Darfur rebel splinter factions, but key rebel groups rejected the accord.
Among its provisions, the Doha peace document calls for a referendum on Darfur's administrative structure.
At least 300,000 people have died in the Darfur conflict that first erupted in 2003 when African rebel groups rose up against the Arab-dominated Khartoum government, according to UN estimates.
Another 1.9 million people are living in camps for those displaced by the violence.
The government puts the total number of dead at around 10,000.
Bashir is wanted by The Hague-based International Criminal Court for alleged crimes against humanity, war crimes and genocide in Darfur.