At least nine people have been killed and several others injured after Sudanese security forces stormed a protest camp in central Khartoum early Monday.
"The protesters holding a sit-in in front of the army general command are facing a massacre in a treacherous attempt to disperse the protest," said a statement from the main protest group.
Sudan's military has so far made no statements.
The protest outside the military headquarters has been the centre of a campaign to bring a civilian government to power.
Talks between protesters and Sudan's military rulers over the transitional period has ended in a deadlock over who would dominate the top decision-making body.
Trump says Iran war deal close as Strait of Hormuz tensions linger
Victims' families mark Air India crash anniversary with prayers and tributes
Fire breaks out at New Zealand's Wellington airport, disrupting flights
Ukraine and Russia trade overnight drone strikes, officials say
UN says Taliban arrest 30 women for violating hijab rules in Afghanistan
