Sudan’s military leaders say they are scrapping all existing agreements with the main opposition coalition and will hold elections within nine months.
The announcement came as the military faced mounting international condemnation for their violent attack on protesters in the capital, Khartoum, which reportedly left at least 30 dead.
The US said it was a “brutal attack”.
The crackdown came after the military and protesters agreed a three-year transition period to civilian rule.
The Transitional Military Council (TMC), which has governed Sudan since President Omar al-Bashir was overthrown in a coup in April, and negotiators for the pro-democracy movement had also settled on the structure of a new administration.
But the TMC’s head, General Abdel Fattah al-Burhan, said in a statement broadcast on state television that they had decided to “stop negotiating with the Alliance for Freedom and Change and cancel what had been agreed on”.
An election in nine months’ time would take place under “regional and international supervision”, he added.
The announcement came after leaders of the pro-democracy movement, who demand that a civilian government take over the running of the country, said they were stopping all contact with the TMC and called a general strike.