Sudanese security forces fired tear gas to disperse hundreds of protesters in the eastern city of al-Qadarif, witnesses said, in what was one of the largest demonstrations the country has seen in recent weeks.
The protests against price rises and other economic hardships that began on Dec. 19 are the most persistent opposition President Omar al-Bashir has faced since he took power in an Islamist-backed coup nearly 30 years ago.
Some Western governments on Tuesday condemned the use of live ammunition against protesters.
Videos of the demonstration circulating on social media showed hundreds of people in al-Qadarif chanting "freedom, peace, justice!" and "revolution is the people's choice." Reuters could not independently verify the footage.
Three residents of al-Qadarif, who were not involved in the protests themselves, said the security forces fired tear gas to break up the protest, which was organized by a group of unions known as the Sudanese Association of Professionals.
The local governor, Al-Tayib Al-Amin, told Reuters the protests were "limited" and that police dealt with the situation "professionally," without specifically addressing the question of whether tear gas had been used.
Since the demonstrations began, security forces have blocked and broken up demonstrations using live ammunition as well as tear gas and stun grenades, witnesses say.
Interior Minister Ahmed Bilal Othman said on Monday that more than 800 people had been detained since protests began nearly three weeks ago.
Authorities say 19 people, including two security officials, have died, while global rights group Amnesty International and Human Rights Watch put the number at double that. At least six of those killed died in al-Qadarif.
Britain, the United States, Canada and Norway said in a joint statement Tuesday they were concerned about the Sudanese government's response to the protests.
"We are appalled by reports of deaths and serious injury to those exercising their legitimate right to protest, as well as reports of the use of live ammunition against protesters," the statement said.
"Furthermore, our countries call upon the government of Sudan immediately to release all journalists, political opposition leaders, human rights activists, and other protesters currently in detention without charge or trial."