Security officers fired barrages of tear gas canisters on protesters demanding a restoration of the transition to civilian rule, witnesses say.
Sudanese security forces have killed a protester as they cracked down on thousands marching for civilian rule.
The medics' announcement on Sunday took the number killed since last year's military coup to at least 79.
More than three months after the October 25 takeover led by General Abdel Fattah al Burhan in the troubled northeast African country, defiant mass rallies demanding a restoration of the transition to civilian rule show few signs of abating.
'Go back to barracks'
"Go back to the barracks," protesters shouted at a heavy deployment of security officers who fired barrages of tear gas canisters, witnesses in the eastern state of Gedaref said.
The coup, one of several in Sudan's post-independence history, derailed a power-sharing arrangement between the army and civilians that had been painstakingly negotiated after the 2019 ouster of longtime president Omar al Bashir.
Sunday's demonstrations also took place in locations including the northern cities of Atbara and Dongola, and in Darfur in the country's west.