Police fired stun grenades to disperse hundreds of students gathered outside South African President Jacob Zuma’s offices in Pretoria on Thursday as violent protests over the high cost of university education rumble on with no resolution in sight.

Weeks of demonstrations calling for the scrapping of university fees, prohibitive for many black students, have highlighted frustration at enduring inequalities in South Africa more than two decades after the end of white minority rule.

Zuma was scheduled to travel to neighbouring Mozambique on Thursday to meet its President Filipe Nyusi.

Around 300 protesters, some of whom hurled sticks and bottles at police, were gathered in a park outside the building where the government has its seat, a Reuters witness said.

The crowd fled when police used water cannon to disperse them, but soon returned and began singing and chanting again under warm summer skies as a police spotter plane circled low overhead. Armoured police cars then drove into the park, forcing the students to flee again.

One student who gave his name as Gift and attends Tshwane University of Technology in Pretoria, said he wanted higher education fees to be scrapped.

“We want to see fees fall and we want our members who have been arrested be released. Even murderers get bail here but students do not,” Gift said. A student leader arrested for taking part in the protests was denied bail this week.

Zuma last week formed a ministerial team to try to resolve the dispute with students, but the government has said it could not allocate extra funds to education at the expense of health or housing.