Sudanese police have fired tear gas to disperse protesters demanding an end to military rule in the capital Khartoum, eyewitnesses say.
Thousands of protesters were chanting “Civilian rule” when police dispersed crowds in several parts of the city, the witnesses told AFP news agency.
On Saturday, paramilitary forces broke up a news conference called by organisers of the protest.
The military ousted President Omar al-Bashir in April.
It followed a popular uprising against his rule. Mr Bashir seized power in a coup on 30 June 1989.
Pro-democracy activists had called for a “million-strong” march on Sunday – the first mass demonstration planned since dozens were killed when the military opened fire on pro-democracy protesters on 3 June.
Tens of thousands of people protested in cities and towns across Sudan to demand the transfer of power to a civilian-led administration.
In Khartoum, police fired tear gas at crowds in the northern district of Bari and in Mamura and Arkweit in the east, AFP quoted witnesses as saying.
Shops were shut in areas where protests were taking place.
A heavy contingent of security forces, including the much-feared paramilitary Rapid Support Forces (RSF), was deployed ahead of the protest.
Protest leader Ahmed al-Rabie told AFP that the RSF had broken up a media briefing called by the Sudanese Professionals Association (SPA) in Khartoum on Saturday.
“Before we could start the press conference, three vehicles from RSF, full of armed men, came to our building and told us not to hold the press conference,” he said.
Everyone in the building was ordered to leave, Mr al-Rabie said.
He told Reuters news agency that the raid was “a violation of liberties that is even worse than the regime of the former president”.
The military said it would hold the opposition responsible for any violence or loss of life in the protests.
Gen Mohamed Hamdan Dagalo, also known as Hemeti, warned of “vandals” and a “concealed agenda” that might take advantage of the demonstrations.
Talks between the Transitional Military Council (TMC) and the opposition collapsed after 3 June and have not resumed despite mediation by the African Union (AU) and Ethiopian Prime Minister Abiy Ahmed.
On Friday, the SPA said two leading members of the opposition had been detained and urged “the international community to demand their immediate release”.