Jan. 25 (Bloomberg) -- AngloGold Ashanti Ltd., Gold Fields Ltd. and Anglo Platinum Ltd. shut their South African mines as the nation's power shortage worsened, threatening growth in the continent's biggest economy.

Mining companies stopped thousands of workers going as much as two miles underground after state utility Eskom Holdings Ltd. told them it couldn't guarantee power today. Anglo Platinum and Impala Platinum Holdings Ltd., the world's biggest platinum producers, also shut most mines. They dropped in Johannesburg trading and precious metals rose to a record.

``Power is like oxygen, it's essential for any half-modern economy,'' said Goolam Ballim, chief economist of Standard Bank Group Ltd., Africa's biggest lender. ``If you're shaving growth, then earnings generation, stock market potential and wealth creation is being eroded.''

Eskom, which supplies 95 percent of the country's power, can't meet demand after the government delayed a decision on expansion by four years. That may cut growth in South Africa by half a percentage point this year, Ballim said, and deter foreign investment in a country with a jobless rate of 25.5 percent.

AngloGold, Africa's biggest gold producer, dropped 3.5 percent to 302.99 rand in Johannesburg trading while Gold Fields fell 8.5 percent to 107.88 rand.

Precious Metals

South Africa is the world's biggest platinum producer and ranks second, after China, for gold output.

``This is very negative for the industry and for the country,'' said Duane Cable, a Cape Town-based gold mining analyst at Coronation Fund Managers Ltd., which oversees the equivalent of $20 billion. ``It's affecting the economy across all industries.''

Eskom on Jan. 17 said it may renegotiate an agreement signed with Alcan Inc. to provide power to a $2.7 billion South African aluminum smelter. Public Enterprises Minister Alec Erwin today said the accord would be honored.

South Africa attracted foreign investment of 25.5 billion rand ($3.6 billion) in the first three quarters of last year.

Eskom sent a request to 138 industrial customers yesterday to cut electricity use, spokesman Andrew Etzinger said. The request followed an ``unprecedented'' number of power cuts yesterday, he added.

Eskom will meet with the users next week to discuss the power ``emergency,'' the company said.

Safety First

Customers were told that the ``safety of plants and people should be a priority,'' Etzinger said. ``It was driven by the need to ensure the integrity of the electricity grid system and prevent a worsening of the situation.''

A shortage of generating capacity was compounded by wet weather, which has damaged coal stocks, Etzinger said. Power cuts are expected to last until at least 2013, Eskom has said.

Eskom Chief Executive Officer Jacob Maroga said he wasn't aware of the mine closures.

South Africa's government said the power cuts won't halt planned industrial projects or threaten its hosting of the 2010 soccer World Cup. It plans to accelerate efficiency programs to save as much as 3,500 megawatts of electricity by 2010, Public Enterprises Minister Alec Erwin told reporters in Pretoria today.

The shutdowns mean entire regions of South Africa are dark for up to five hours a day, triggering traffic jams and emptying shopping malls.

Coal Mines

Anglo American Plc, the world's second-largest mining company, stopped production at five of its nine South African coal mines. Three of the mines still operating supply Eskom, which generates most of its power by burning coal.

While BHP Billiton Ltd.'s collieries were all operating, two of its manganese mines in the Northern Cape were shut, spokeswoman Bronwyn Wilkinson said. Power supply was also cut to the company's three aluminum smelters in southern Africa, she added.

Samancor Chrome Ltd., the world's second-biggest ferrochrome producer, plans to shut all its furnaces in South Africa within the next 24 hours. The shutdown, requested by Eskom, may last two to six weeks, the Johannesburg-based company said.

Xstrata Plc, the world's fourth-largest copper producer, halted production at its ferrochrome furnaces and said its vanadium and platinum operations were also affected. The company's 13 coal mines were still operating.

Gold Output

South Africa's daily gold output averaged 23,245 ounces in the third quarter, according to the chamber. Other South African mining companies have also shut operations, the South African Chamber of Mines said without being specific.

China overtook South Africa as the world's largest gold producer last year as its production climbed 12 percent to 276 metric tons, while South Africa's output declined 8.1 percent to 272 tons, its lowest since 1922, London-based researcher GFMS Ltd. said on Jan. 17.

``The short-term impact is lower production and lower revenue which may hurt profits and cash flow, depending on how long it lasts,'' said Anwaar Wagner, who helps manage the equivalent of $57 billion at Old Mutual Investment Group South Africa, the continent's largest private money manager.

Electricity disruptions could affect cooling systems needed to keep underground temperatures within levels of ``human tolerance,'' the chamber said. Power is also needed to operate hoisting equipment.

Temperature Rising

``We didn't send down any staff at our South African mines for the day shift today after being told of possible electricity supply interruptions,'' said Steve Lenahan, a spokesman for AngloGold.

Only emergency maintenance work is being carried out at Gold Fields' South African mines, which produce about 7,000 ounces a day, spokesman Willie Jacobsz said in an interview from Johannesburg. Eskom can't guarantee power supply for two to four weeks, he said.

Harmony Gold Mining Co., the country's third-biggest gold producer, canceled today's shifts, according to spokeswoman Amelia Soares.

Impala, the world's second-biggest platinum producer of the metal, said it will lose about 3,500 ounces of platinum after it shut deep-level mines in South Africa. The company's refinery and shallower operations are operating normally, spokeswoman Alice Lourens said.

Northam Platinum Holdings Ltd., the operator of the world's deepest platinum mine, isn't running plants and smelters at full capacity, said spokeswoman Marion Brower.

Gold for immediate delivery gained as much as $10.89, or 1.2 percent, to a record $923.73 an ounce and traded at $911.23 at 4:29 p.m. London time. Platinum jumped as much as 5.6 percent to a record $1,701 an ounce.

To contact the reporter on this story: Vernon Wessels in Johannesburg at vwessels@bloomberg.net

Last Updated: January 25, 2008 11:44 EST