One person is reported dead as Sudanese police dispersed protests in Khartoum and two other cities against the canceling of fuel subsidies by President Omar al-Bashir.
In power since 1989, Bashir has avoided an "Arab spring" uprising of the sort that unseated other rulers in the region, but many in Sudan complain about soaring food prices, corruption, harassment from security services, violent conflicts, high unemployment and a lack of infrastructure.
The government doubled prices for fuel and cooking gas on Monday to bring its budget under control. The Arab African country lost three-quarters of its oil reserves – its main resource - when South Sudan became independent in 2011.
Within hours of petrol stations adjusting their price displays, some 800 protesters gathered in the centre of Wad Madani, capital of Gezira state south of Khartoum, shouting "No, No to price hikes," witnesses told Reuters.
Others called on Bashir to resign, yelling "Go, go!"
One person is thought to have been shot dead in Wad Madani after protesters set fire to the ruling National Congress Party buildings, according to local news reports and social media.
Police downplayed events and said security forces had controlled a "limited riot” using tear gas, according to SUNA the state news agency.
Late on Sunday, Bashir held a televised news conference lasting two hours to defend his abolition of fuel subsidies. He promised to use much of the money saved to help the poor and increase salaries for civil servants.
But many Sudanese have grown impatient with years of what they see as economic and political crises caused by consistent mismanagement and US trade sanctions.
"The government ... has no idea of what people are going through. I am ready to join any protest against the lifting," said 41-year old Ahmed Lassan, an unemployed worker.
Petrol stations in the capital Khartoum raised the price of a gallon (3.8 litres) of petrol on Monday to 21 pounds (almost $3 based on black market prices), from 12 pounds.
A gallon of gasoline now costs 14 pounds, up from 8.5 pounds. The prices for a cylinder of cooking gas rose to 25 pounds from 15 pounds.
Sudan produces too little to feed its 32 million people.
Even basic food imports such as wheat arrive by ship in Port Sudan, before they get trucked for days across the vast country, spurring food-price inflation.
The government claims annual inflation has fallen to 23.8 percent in July from 37.1 percent in May but independent analysts dismiss the figures and put the rate at 50 percent or even higher.
The Sudanese pound is worth barely a third of its value against the dollar on the black market at the time of the South’s succession.