Workers and students stayed at home after public transport was disrupted. Analysts say a complete shutdown of the economy could scare off foreign investors.

Thousands of workers assembled outside city hall in the capital, Pretoria, while hundreds of supporters gathered in Cape Town, which hosts the parliament.

The nearly two million-strong Cosatu said the action will be a warning to employers who may want to sack workers because of a downturn in profits due to a power supply crisis.

"We are adamant that workers should not be asked to pay for government's failure to invest in electricity," Patrick Craven, Cosatu's spokesman said.

South Africa, with 23 per cent unemployment, has felt the global impact of rising food and oil prices, which workers say has pushed them deeper into poverty.

"We are poor, we are hungry and our wages are no longer coping with our demands and the demands of feeding and clothing our families," Zwelinzima Vavi, Cosatu's general secretary, told protestors outside the closed gates of parliament.

"This is not the last action we are going to be seeing. If government is not going to move with the necessary speed, we will again hit them where we know they will feel the pain," he said.

Charles Davids, a bakery worker who has four children, said: "The government must reverse the high food and petrol prices. The poor are getting poorer."

Cosatu has vowed to fight President Thabo Mbeki's market-friendly and pro-business stance, and wants his government to subsidise basic staples and pay workers better.

Workers fearful

South Africa's mine workers are particularly concerned about possible job cuts because a five-day power cut in January and the rationing of electricity to mines has cut output and earnings.

"We are adamant that workers should not be asked to pay for government's failure to invest in electricity," Patrick Craven, Cosatu's spokesman, said.

Anglogold Ashanti said the one-day strike would shut down all of its mines in the country.

"There will be a widespread impact," Alan Fine, a company spokesman, said. "All of our operations will be shut down."

Anglo Platinum, the world's top platinum producer, and Impala Platinum, ranked second, may also be disrupted.

The one-day strike helped push global platinum prices up 3 per cent and added to investor worries over South Africa.

Analysts said the strike could further dent a slowing economy, with growth seen at around 3 per cent this year from an average 5 per cent over the past four years.

"Our economic growth rate has already been slowed down substantially in response to tight monetary policy, lower global demand and the electricity shortfall," Elna Moolman, economist at Barnard Jacobs Mellet Holdings, in Johannesburg said.

"This strike will just add to the downside risk for GDP [gross domestic product] growth this year," she said.

BHP Billiton's aluminium smelters, Anglo American's coal and iron ore mines and refineries on South Africa's coastline were also affected, raising concerns that this could worsen the country's power supply woes.

A national commuter train service was also affected as was public transport on the country's roads, leaving commuters stranded.

South African stock market and the rand currency largely shrugged off the strike, however, analysts said.