Image copyright AP Image caption Civil society groups had petitioned President Omar al-Bashir over the planned elections
Ten protesters, four of them women, have been shot dead in the Sudanese capital, Khartoum, according to local medical sources.
Some protesters were armed with weapons but it is unclear if they were linked to the unrest, in which 22 were killed earlier.
Sudanese police have not confirmed the deaths.
They said that five security personnel were killed in the protests and that four protesters died in police custody.
The demonstrations, which started two weeks ago, were sparked by subsidies being withdrawn for cooking gas and diesel, causing a sharp increase in fuel prices.
Khartoum-based doctor Ahmed Ismail has told the BBC that protesters ran from the scene in panic when they were confronted by security forces.
“They shouted God is great, we don’t accept this, and you should kill us. They entered some buildings and blocked a road,” he said.
BBC correspondent Nour Lawali says protests were continuing in Khartoum on Friday night.
Image copyright EPA Image caption There have been sometimes violent clashes with security forces in Khartoum
Health officials in Sudan have said that total clashes across the country in which 173 people have been injured have not been directly related to those protests.
But, despite the ongoing unrest, Sudanese President Omar al-Bashir on Thursday called for new elections to be held next year.
Mr Bashir won a disputed election in 2010.