Sudan's President Omar al-Bashir has declared a national state of emergency, dismissed the federal government and sacked all state governors.
Mr Bashir made the announcement in a TV address to the nation, but later appointed members of the security forces as replacement governors.
Earlier, Sudan's National Security and Intelligence Services (NISS) said that Mr Bashir would be stepping down.
Mr Bashir has been the focus of anti-government protests in recent weeks.
Protesters took to the streets after the announcement in the city of Omdurman, witnesses said, but were met with tear gas by police.