Cape Town (AFP) - Riot police were deployed to South Africa's parliament as it collapsed into chaos on Thursday with a group of radical lawmakers yelling at President Jacob Zuma: "Pay back the money".

The unprecedented upheaval came as Zuma was grilled over the $24 million (18 million euros) of taxpayers money spent on "security upgrades" at his private residence.

Led by firebrand Julius Malema, a former member of the ruling party, about 20 members of his Economic Freedom Fighters party defied repeated orders to leave from Speaker Baleka Mbete.

Dressed in their usual "workers solidarity" outfits of red overalls, hardhats and maid's uniforms, they refused to budge -- chanting, pointing fingers and banging desks.

The speaker called for help from security and all MPs were asked to vacate the chamber while the EFF members were dealt with.

Zuma, who had at first smiled at Malema's display, was among the first to leave.

For around 10 minutes, live broadcasts of parliament showed the EFF members alone in the assembly and still chanting. The broadcast was then cut.

Riot police arrived and a forcible eviction appeared on the cards before negotiations with the EFF led to the suspension of the session. Zuma did not reappear.

A report by South Africa's public protector had called on Zuma to repay some of the millions spent on items such as a swimming pool, amphitheatre, cattle pen and chicken run at his rural home in Nkandla.

Zuma failed to meet numerous deadlines for a response, and then said he had appointed the police minister to decide whether he needed to pay back any of the money.

The EFF has risen from nowhere in the past few years on the back of populist policies such as the nationalisation of mines and banks, and the seizure without compensation of white-owned land.

The disruption of parliament was the latest in a series of publicity stunts by the EFF, which won 25 seats in the 400-seat parliament in May elections.

Last month, police threw stun grenades and fired rubber bullets when the EFF stormed the provincial legislature in the country's economic centre Johannesburg after they were evicted for wearing their "workers" outfits.

ANC spokesman Zizi Kodwa said "the violent nature in which the EFF engages on issues is likely to take South Africa backward.

"We warn them not to take us back to the past where we will have no option but to defend our hard won democracy."