In what is becoming a trend across the region since the Jasmine Revolution in Tunisia, student protesters clashed with riot police in Khartoum.
Opposition organizers used social networking sites on the Internet to rally support for demonstrations against political repression and poor economic conditions, The Wall Street Journal reports.
Authorities told the Journal many of the student protesters were chanting slogans on solidarity with the uprisings in Tunisia and Egypt.
Bashir, wanted for crimes against humanity by the International Criminal Court, led his government in a civil war against South Sudan until a peace agreement was brokered in 2005.
Sudanese organizers said they weren't affiliated with any opposition party, though they felt it was time for Bashir to stand down.
Sudanese demonstrators, the Journal said, picked Sunday for their protests to coincide with the announcement of the preliminary results of a referendum for South Sudan's secession.
Voters this month cast ballots regarding independence in South Sudan. Early results show nearly all of the eligible voters backed the referendum.