Sudan's President Omar al-Bashir has issued a decree banning political parties from holding meetings without permission from the authorities, the official SUNA news agency has reported.
"No political party has the right to hold meetings and conferences inside their areas without first obtaining permission from the relevant authorities," SUNA late on Monday reported the decree as reading.
The decree comes just a week after Bashir assured a meeting of party leaders they had freedom to operate in the run-up to a "national dialogue" he has promised to hold to address urgent demands for change in his 25-year regime.
No political party has the right to hold meetings and conferences inside their areas without first obtaining permission from the relevant authorities
At the April 6 meeting in Khartoum, Bashir assured party leaders they were free to conduct activities inside or outside their offices, "according to law".
A day later, however, the Reform Now party said security agents had prevented it from holding a discussion forum and had detained the leader of its student wing, Emad Al-Dien Hashim.
Reform Now was formed in December by Bashir's ex-adviser Ghazi Salahuddin Atabani after the ruling National Congress Party ousted him.
Critics have said Bashir's political dialogue is just a way for the elite to hang on to power without properly addressing the country's problems.
An alliance of small opposition parties has refused to join the dialogue, which Bashir announced in January, unless the government meets several conditions.
These include declaring a ceasefire with the country's armed rebels, and abolishing all laws that restrict freedoms.
The Revolutionary Front, which comprises armed groups from Kordofan, Blue Nile and Darfur, on Sunday rejected participation in the dialogue, describing it as a "farce".