South African President Jacob Zuma on Friday abandoned proposed hikes to university fees after days of protests culminating in police firing stun grenades at students outside government headquarters.

Some demonstrators tried to force their way towards the Union Buildings in the capital Pretoria, tearing down a security fence, setting fire to portable toilets and hurling bricks at police lines in chaotic scenes.

Zuma had been due to address the crowd after meeting with student leaders and university officials inside the buildings, but instead he read a short statement at a televised press briefing.

"We agreed that there will be a zero increase of university fees in 2016," he said.

"In the long term, there is a package of issues that was raised at the meeting that needs to be followed up -- these include free education, institutional autonomy (and) racism."

Universities around the country have been closed over the last week as students protested against the proposed fee rises, which they say would mean poorer black youths are unable to study for degrees.

The issue of education fees has ignited widespread frustration over a lack of opportunities for young people since the end of apartheid, worsened by a weakening economy and high unemployment.