Police fired tear gas on Friday to disperse demonstrators who had taken to the streets of the Sudanese cities of Omdurman and Atbara to protest price hikes and corruption.
Public anger has been building over price rises, inflation and other economic hardships, including a doubling in the cost of bread this year and limits on bank withdrawals.
A government decision to raise the price of a loaf of bread this week from one Sudanese pound to three (from about two to six US cents) sparked protests across the country on Wednesday.
In Rabak, capital of the White Nile State, protesters Friday set fire to a number of government buildings, including a ruling party headquarters, prompting authorities to declare a state of emergency.
They had declared states of emergency and curfews in cities in at least four of Sudan's 18 states, according to local media.
The protests that began after noon prayers were smaller than those on Thursday with demonstrators some calling for the overthrow of the regime.
Ten people were killed in the third day of demonstrations, bringing the total to 17 since their eruption.
In the capital's twin city Omdurman, a witness said protesters chanted "the people want the fall of the regime" and "freedom, freedom.”
"Riot police fired tear gas at the demonstrators," the witness added.
Dozens also demonstrated on Road 60, a main artery in eastern Khartoum that links the city center to the south of the capital, another witness said.
They demanded the government's ouster, the witness said on condition of anonymity, adding that the protesters were dispersed by riot police.
Protests were reported in other cities, including in El Obeid, southwest of Khartoum.
A government spokesman blamed “infiltrators” for derailing peaceful demonstrations into “subversive activity.”
Bashar Jumaa warned that the government "will not be lenient" with those who set state buildings on fire or caused other damage to public property.
Demonstrators on Thursday torched ruling party offices in the cities of Dongola and Atbara, while security forces fired tear gas to disperse crowds in Khartoum, where small and scattered protests continued into the night.
The official Sudan News Agency on Friday said schools in the Sudanese capital Khartoum would be indefinitely closed starting Sunday.
Web users reported problems accessing the internet, and some accused the authorities of blocking social media including Facebook, Twitter and WhatsApp in a bid to stop protesters communicating.
Sudan’s economy has struggled to recover from the loss of three quarters of its oil output - its main source of foreign currency - when South Sudan seceded in 2011.
