Fresh rioting erupted in Sudan on Thursday as protests sparked by the government scrapping fuel subsidies raged into a fourth day and medics reported an overall toll of 29 dead.
Thousands of people protested in the capital and in the country's north, calling for the downfall of the government.
As the protests escalated, the largest since President Omar al-Bashir seized power in 1989, the leader wanted by the ICC for alleged war crimes and genocide cancelled a planned trip to the UN General Assembly.
Thursday's rioting erupted in the Inqaz district south of Khartoum where some 3,000 people burned tyres and hurled stones at passing cars, witnesses said0.
Police responded with tear gas and rubber bullets, but there were no immediate reports of casualties.
In Port Sudan on the Red Sea, 1,000 kilometres (600 miles) northeast of Khartoum, witnesses reported about 1,000 people demonstrating before being dispersed by tear gas.
"No to high prices, no to those who make money from religion," they shouted, referring to Sudan's Islamist regime.
Earlier, a hospital source in Khartoum's twin city of Omdurman told AFP that "we have received the bodies of 21 people" since the protests first erupted on Monday, adding that all were civilians.
Another eight people were killed elsewhere, witnesses and relatives said.
Thursday's protests came after anti-riot forces deployed from early morning at major road intersections in Khartoum, an AFP correspondent said.
Rioting in Khartoum districts had continued late into Wednesday night.
"Freedom, freedom!" and "The people want the fall of the regime!" shouted protesters, many of them students, borrowing the refrain of the Arab Spring protests which toppled several governments in 2011.
"We came out, we came out against those who have stolen our sweat," they chanted, according to a video uploaded on YouTube.
Protesters tried to torch a tourism ministry building in southern Khartoum, witnesses said, adding that its exterior was scorched.
Khartoum governor Abdel Rahman al-Khidr warned on state television overnight that "the government will strike with an iron fist against those who damage public property."
The broadcaster showed footage of damaged or burned vehicles, buildings and petrol stations, and accused "outlaws" of being behind the violence.
It said police intervened to prevent "law-breaking and damage to private and public property."
Petrol stations remain closed on Thursday.
The protests first erupted in Wad Madani in Gezira state of central Sudan, the scene of the first death on Monday. They have also spread to Nyala, capital of South Darfur state.
Many students have been reported as taking part in the trouble, and the education ministry closed schools until September 30.
Internet access resumed on Thursday, users said, after being cut Wednesday. It was unknown if this was a fault or a deliberate move by the authorities.
The US embassy has urged its citizens to avoid flashpoint areas, saying it had received "regrettable" reports of casualties and warning of further protests.
Opposition leaders, including former premier Sadeq al-Mahdi, met at around midday.
With the lifting of subsidies, oil prices at the pump have shot up to 20.80 Sudanese pounds ($4.71) a gallon from 12.50 pounds ($2.83), and diesel has risen from 8.50 pounds a gallon to 13.90 pounds.
Inflation is already running at 40 percent.
Bashir said on Sunday fuel subsidies had reached "a level that is dangerous for the economy."
Khartoum lost billions of dollars in oil receipts when South Sudan gained independence two years ago, taking with it about 75 percent of the formerly united country's crude production.
Official media publish only the government's view, and the independent Al-Jarida did not appear on Thursday in protest at censorship, its editor told AFP.
"We decided not to publish in protest at the security services' decision to forbid publication of all information about the protests except police bulletins," Idriss al-Dumah said.
Bashir, meanwhile, had been scheduled to travel to New York to address world leaders at the UN General Assembly on Thursday.
But a UN spokesman told AFP said that his foreign minister, Ali Karti, would address the world body on Friday instead.
Under international accords, the United States would not have been able to refuse Bashir a visa. But it could have detained him on arrival.
The International Criminal Court had urged the United States to arrest Bashir who is wanted by the court at The Hague court on 10 counts of war crimes, crimes against humanity and genocide in the Darfur conflict.