Pretoria: Thousands of South African students demanding lower university fees gathered on Friday for a march on the historic seat of government in Pretoria, a sign of the post-apartheid 'Born Free' generation flexing its political muscles.

Student leaders are due to meet President Jacob Zuma and university professors at the Union Buildings to press their case, arguing that the costs of tuition are too high for many blacks, perpetuating South Africa's racial inequalities.

Tuition fees vary across different universities, but can run as high as 60,000 rand ($4,500) for medical students in a country where white households earn six times more than black households, according to official figures.

Protests - some of them violent - have broken out at universities across the country this week, taking the ruling African National Congress (ANC) by surprise.

On Wednesday, riot police threw stun grenades at students who stormed the parliament precinct in Cape Town as Finance Minister Nhlanhla Nene delivered his interim budget in which he painted a gloomy outlook for Africa's most advanced economy.

Thousands of students from Wits and the University of Johannesburg marched through South Africa's commercial capital on Thursday and gathered outside Luthuli House, the headquarters of the ANC where they handed a list of demands to the ruling party's Secretary General Gwede Mantashe.

In Cape Town, students marched in the city on Thursday and engaged police in skirmishes as officers fired stun grenades.

Low growth since a 2009 recession has forced the government to keep a lid on spending, meaning that it has little spare cash to offer students in the form of enhanced subsidies.

Analysts say loosening the purse strings could also encourage other sectors of society to push for greater government assistance.

South Africa has a million students in further education, a figure that the ANC wants to increase to 1.5 million by 2030.