"If heads must roll we cannot allow it be the workers who take the knock," it said in a statement after its central committee met over the weekend.

The mining industry, a big foreign exchange earner and employer, ground to a halt for five days in January as blackouts intensified and millions of homes were left without power.

Gold Fields, the world's fourth-largest gold miner, warned last week of potentially 6,900 job cuts as it scales back production at lower grade mines because of power rations.

On Friday, Public Enterprises Minister Alec Erwin sought to ease the concerns of unions who have threatened street protests if jobs are lost as a result of the power crunch.

South Africa's main labour federation COSATU, which is also an ally of the ruling ANC, has threatened to strike if any workers in the country lose their jobs due to the crisis that it blamed on government negligence.

The SACP said it would engage in a period of mass activism in the coming months and would "fully support COSATU struggles in defence of jobs."

Shortages have increased foreign investors' worries over South Africa, stirred anger at the failure of President Thabo Mbeki's government to prevent blackouts and raised questions over the country's ability to host the 2010 soccer World Cup.

Critics say the government has failed to invest in boosting state utility Eskom's power generation capacity.

"It is absolutely unacceptable that the mining houses, now benefiting from huge surges in international commodity prices, should be threatening retrenchment of thousands of mine-workers," said the SACP.

"These threats from the mining houses and other business quarters need to be seen for what they are -- they are seeking leverage to retain their historic monopoly over energy policy including energy pricing."

As it scrambles to fix the crisis, Eskom said it planned to spend 343 billion rand increasing its generating capacity over the next five years.

On Friday, it said it had awarded two contracts worth 31.5 billion rand for its Bravo project coal-fired power station to be completed by 2017.

Hitachi Power Africa, a unit of Hitachi Ltd, won an 18.5 billion rand contract to construct the power plant's boilers and France's Alstom was awarded a 13 billion rand contract for the turbine island works.