Defiant crowds have spent the night on the streets of Sudan’s capital, Khartoum, ignoring a curfew declared by the military.
Long-time President Omar al-Bashir was overthrown and arrested on Thursday after months of street protests.
But demonstrators say the military council which has taken power is part of the same regime.
The fresh stand-off has raised fears of a violent confrontation between protesters and the army.
There is also a real danger that different elements of the security forces and militia could turn their guns on each other, says BBC World Service Africa editor Will Ross.
The UN and the African Union have both called for calm.
Sudan is due to reopen its airspace on Friday, following a 24-hour suspension, but land and maritime borders will remain closed, the military council has said.
The curfew, in force from 22:00 local time (20:00 GMT) to 04:00, was declared for the “safety” of citizens, state media said.
The armed forces and the security council would carry out their “duty to uphold peace and security and protect citizens’ livelihoods”, it said.