Sudanese security forces fired tear gas on Sunday after demonstrations broke out at the University of Khartoum, where nationwide protests against high prices began last month, a witness said.

"There are some demonstrations in the main campus," and authorities used gas to try to clear the area, he said, asking not to be identified. He said "a few" people were protesting but could not give a more accurate number.

The university is where an unprecedented three weeks of national protests began on June 16, when students first voiced their opposition to high food prices.

After President Omar al-Bashir announced austerity measures, including tax hikes and an end to cheap fuel, the protests spread to include a cross-section of people around the capital and in other parts of Sudan.

Often in groups of 100 or 200, they burned tyres, threw stones and blocked roads in a daily call for regime change. The protests, lately focused on Fridays, have been met by what the European Union called a "a violent crackdown."

Bashir has played down the demonstrations as small-scale and not comparable to the Arab Spring uprisings in Egypt and elsewhere, maintaining that he himself remains popular after 23 years in power.