Protest organizers said security services stormed their offices without warning and forced them to call off a press conference. Nationwide marches would still go ahead on Sunday, however, they announced.
Security forces raided the offices of Sudan's opposition group, the Sudanese Professionals' Association (SPA), the group said late on Saturday, forcing them to nix a press conference ahead of major protests.
The SPA and the military have clashed repeatedly in recent weeks, disagreeing over the timeline for a transition to democracy after the protest movement ousted former strongman President Omar al-Bashir. Since talks between the two groups broke down earlier this month, a violent crackdown has killed at least 128 people across the country, according to protest organizers.
Demonstrators have repeatedly accused the military of trying to make a power grab in Bashir's absence.
"This represents a violation of liberties that is even worse than the regime of the former president," SPA spokesman Ahmed al-Rabie told Reuters news agency after the raid on their offices.
"This is a bad sign for the atmosphere of mediation between the two parties."