Sudanese police beat and arrested students on Sunday as protests broke out throughout Khartoum demanding the government resign, inspired by a popular uprising in neighboring Egypt.
Hundreds of armed riot police fired tear gas on students demonstrating in central Khartoum and in at least two universities in the capital, which were surrounded by police reinforcements. At one, students hurled stones at police cars.
Police beat students with batons as they chanted anti-government slogans like: "We are ready to die for Sudan" and "Revolution, revolution until victory."
Groups have emerged on social networking sites calling themselves "Youth for Change" and "The Spark," since the uprisings in nearby Tunisia and close ally Egypt this month.
"Youth for Change" has attracted more than 15,000 members.
"The people of Sudan will not remain silent anymore," its Facebook page said. "It is about time we demand our rights and take what's ours in a peaceful demonstration that will not involve any acts of sabotage."
Sudan has a close affinity with Egypt as the two nations were united under British colonial rule. The unprecedented scenes there inspired calls for similar action in Sudan, where protests without permission, which is rarely given, are illegal.
Before Tunisia's popular revolt, Sudan was the last Arab country to overthrow a leader with popular protests, ousting Jaafar Nimeiri in 1985.
Opposition leader Mubarak al-Fadil told Reuters his two sons were arrested on their way to the central protest.
Editor-in-chief of the al-Watan daily paper Hussein Khogali said his daughter had been detained by security forces since 8 a.m. (0500 GMT) accused of organising the Facebook-led protest.
Pro-government newspapers carried front page warnings against protests which they said would cause chaos and turmoil.
The Sudan Vision daily's editorial blamed the opposition.
"Our message to those opposition dinosaurs is to unite their ideas and objectives for the benefit of the citizens if they are really looking for the welfare of the Sudanese people," it read.
Sudan is in deep economic crisis which analysts blame on government overspending and misguided policies. A bloated import bill caused foreign currency shortages and forced an effective devaluation of the Sudanese pound last year, sparking soaring inflation.
Early this month the government cut subsidies on petroleum products and key commodity sugar, triggering smaller protests throughout the north.
Sunday's protests coincided with the first official announcement of results for a referendum on the oil-producing south's secession from the north showing an overwhelming vote for independence, which many in the north oppose.