Sudanese security forces have fired tear gas and live ammunition to disperse protesters setting up barricades in Khartoum.
At least one person was killed in the northern district of Bahari according to doctors aligned to the opposition.
Campaigners called for ongoing civil disobedience from Sunday to make it as difficult as possible for the military to govern Sudan.
It comes days after a military crackdown left dozens dead.
A number of Sudan’s bank, airport and electricity workers were arrested ahead of a strike against the military rule, the main protest group says.
The Sudanese Professionals Association (SPA) says employees are also being threatened by the authorities to scare them into going to work instead of taking part in the nationwide strike.
The ruling Transitional Military Council (TMC) has made no comment.
The military took over Sudan after persistent protests led to the ousting of long-time President Omar al-Bashir in April. They promised a transition to civilian rule.
But pro-democracy campaigners say the military council cannot be trusted after Monday’s crackdown against a sit-in demonstration in Khartoum – and they have rejected an offer of talks.
In a separate development, three opposition figures involved in mediation efforts have been arrested.
The RSF, formerly known as the Janjaweed militia, gained notoriety for brutal atrocities in the Darfur conflict in western Sudan in 2003.
Khartoum residents have told the BBC that they are living in fear in the capital.
A number of women arrested by the RSF said they were repeatedly beaten with sticks and threatened with execution. They said RSF troops told them to run for their lives, then opened fire. Other victims, they said, were forced to drink sewage water and urinated on.
On Thursday the African Union suspended Sudan’s membership “with immediate effect” and warned of further action if power was not transferred to a civilian authority.