Sudanese riot police armed with batons and tear gas fought with student protesters in Khartoum on Wednesday, June 20 said witnesses, in a fourth day of anti-government demonstrations, according to Reuters.

Student groups, who have led the Khartoum rallies against planned government spending cuts, have sought to leverage anger over rising prices into a wider protest movement, but previous demonstrations have failed to gain broader momentum.

The Arab-African nation has faced soaring food prices and a weakening currency since South Sudan seceded a year ago, taking with it about three quarters of the country's economically-vital oil output.

On Wednesday, riot police carrying batons blocked off a major road and chased scores of students in the streets around the University of Khartoum, activists and two witnesses said. The smell of tear gas hung in the air.

The student demonstrators chanted "the people want to overthrow the regime" and threw stones at the police, the witnesses said.

President Omar Hassan al-Bashir said on Monday Sudan would gradually abolish fuel subsidies, cull the number of civil servants on its payroll, and raise taxes on consumer goods, banks and imports to plug its budget deficit.

Also on Wednesday, Sudanese authorities released an Agence France-Presse correspondent after detaining him at the University of Khartoum, the French news agency said.

British national Simon Martelli had been detained at around midday on Tuesday while taking pictures and talking to students. He was held for more than 12 hours without charge, AFP reported.

Officials at the security services and the Foreign Ministry were not immediately available to comment.