Six people were killed and 20 others wounded Wednesday in tribal clashes in the Sudanese Red Sea port town of Suakin, medics said.
Authorities declared an overnight curfew in Port Sudan and nearby Suakin in a bid to calm the situation.
"The victims were attacked with knives and swords and were transported to Port Sudan general hospital," a committee representing doctors in Red Sea state said.
Witnesses said demonstrators had cut off streets in the two cities in protest at Prime Minister Abdalla Hamdok's decision Tuesday to dismiss the governor of Kassala state, who belongs to the Beni Amr tribe.
The appointment in July of Saleh Ammar as governor of the eastern state of Kassala had aroused the anger of the Beja, the other major tribe in the region.
At the end of August, three people died and another dozen were wounded in tribal clashes following the appointment.
Since then, tensions have been running high in the east of the country.
Last week, members of the Beja tribe blocked the docks in Port Sudan, the country's economic lifeline.
They were protesting against a peace agreement signed on 3 October in Juba between rebel groups and the government that includes a section on the eastern region.
The Beja fear their tribe will be under-represented in regional legislative and executive bodies under the Juba agreement, to the benefit of the Beni Amr.