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.

Iran's supreme leader, in first remarks, vows to keep strait closed
Four Bahrainis arrested for spying for Iranian Guard
Two US sailors injured after non-combat fire aboard carrier in Red Sea
First train to Pyongyang in six years leaves Beijing as neighbours revive link
Six vessels attacked in Gulf, Strait of Hormuz
IEA announces record oil stockpile release over Iran war supply disruptions
UN Security Council adopts resolution condemning Iran attacks on Gulf states
Oman works to contain fire at Salalah port after drones strike
