Sudan's opposition said security forces raided their offices late Saturday and blocked a press conference ahead of major protests against military rule.
"This represents a violation of liberties that is even worse than the regime of the former president (Bashir)," a spokesperson for the Sudanese Professionals' Association (SPA) said. "This is a bad sign for the atmosphere of mediation between the two parties."
The "million-strong march" is to press the military council to hand power over to civilians.
Talks between the two groups collapsed earlier this month when security forces stormed a protest sit-in in central Khartoum on June 3, killing at least 128 people.
Demonstrators have repeatedly accused the military of trying to make a power grab following the ouster of Omar al-Bashir.

Qatar busts two cells linked to Iran’s Revolutionary Guard
Jordanian airspace reopens after 'comprehensive review'
Iran vows to attack any ship trying to pass through Strait of Hormuz
Drones target fuel tanks at Oman’s Duqm Port
