Sudan said on Tuesday 13 people were killed and 42 injured in days of clashes between rival ethnic groups in its Red Sea port, state media reported.
Violence broke out in the eastern city of Port Sudan on Sunday evening, the SUNA news agency said, quoting medics who had treated the wounded.
Police sent in reinforcements and have imposed a night-time curfew, the statement added.
Fighting began when protestors from the Nuba people, demonstrating against a new governor, entered a district of the Beni Amer group.
There is long standing hostility between the groups.
The Nuba originate from the South Kordofan region, an area that suffered from the decades of civil war.
The Beni Amer people come from eastern Sudan.