The fight for control of Newmont Mining Corp. has raised concern among antiapartheid activists both in and out of Congress about the extent of South African investment in the United States.

In an effort to thwart a takeover bid from corporate raider T. Boone Pickens Jr., Newmont last month turned to its largest shareholder, Consolidated Gold Fields PLC, for help. Consolidated, a British company ultimately controlled by South African interests, immediately staged a dazzling "market sweep." In two days, the company spent more than $1.5 billion to buy 16 million shares of Newmont on the open market, nearly doubling its stake in the New York-based company to 49.7 percent.

Pickens' investor group, Ivanhoe Partners, has filed suit over Consolidated's tactics, and the stock purchases are temporarily being held in escrow pending the outcome of the legal dispute. But if they are allowed to stand, Consolidated will have gained virtual control over a company that recently has announced plans to become North America's No. 1 gold producer, and claims the biggest gold reserves on the continent.

Consolidated's increased ownership of Newmont increases the American investment base of a tangled web of companies controlled by South African interests. Several industry analysts said they believe the South Africans, worried about the political and economic climate in that nation, are attempting to move money abroad to safer havens like the United States, even though South African law makes it very difficult to invest money abroad.

That investment strategy is being attacked by antiapartheid activists, who argue that the best way to end South Africa's system of racial separatism is to economically isolate the nation. In addition to previous efforts to force American companies to withdraw from their investments in South Africa, the activists now are calling for limits on South African investment in the United States.

"I'm very upset that South African business interests can have the opportunity to buy into American businesses to the extent that they have," said Rep. Mickey Leland (D-Tex.), who recently introduced legislation calling for a ban on investment in the United States by South African mining companies. "They're finding lucrative markets here. ... I don't think we should extend them the privilege of participating in our American society."

"When you start talking disinvestment, we usually have meant U.S. corporations in South Africa getting out," said Jackie Wilson, of the Washington Office on Africa, an antiapartheid activist group. "But the meaning has had to expand."

"We should stop trade and investment both ways," said Randall Robinson, director of TransAfrica, a Washington-based activist group. "We not only have to stop investment going in, we have to stop it from coming out, as well. The object is to isolate, as much as possible, South Africa."

It is difficult, if not impossible, to estimate just how much money South African corporations and individuals have invested in the United States. The Department of Commerce's Bureau of Economic Analysis, for instance, says that direct South African investment in the United States last year actually shows a $19 million deficit, apparently because of losses in businesses in which there was investment.

But hundreds of millions of dollars more in South African investment has come into the United States in a roundabout manner through other nations in recent years. A study done five years ago by corporate researcher Ruth Kaplan for the Africa Fund, a New York-based antiapartheid group, found that one South African company, Anglo American of South Africa Ltd., at that time had investments, usually through companies in other nations, in more than 100 American companies. Most of the companies, including Newmont Mining, were in the mining business or other natural resource industries.

Anglo American -- which is said to control 60 percent of the companies on the South African stock exchange -- is believed to be by far the largest South African investor in the United States. "Anglo American is the big company that we're talking about in terms of South Africa," said Richard Knight, a research associate at the Africa Fund.

Last week, Anglo American gave up one of its U.S. investments. A 14 percent stake in Salomon Inc., which was held by an Anglo American subsidiary, was sold back to the investment banking firm for $809 million, in part, analysts speculated, to help finance the purchase of Newmont stock by Consolidated, which is controlled by Anglo.

South African currency laws have kept investment from flooding into the United States, experts claim, by putting severe limits on how much money South African businesses can send out of the country. But some investors, like Anglo American, managed to get hundreds of millions of dollars out into foreign subsidiaries before the investment rules were put into place in the 1970s. They have built on that offshore base ever since, reinvesting the money earned abroad.

The United States is not the only nation in which South African money is being invested. Businesses in Europe, Australia, Latin America and Canada also have been purchased with South African money. But the United States is increasingly seen as the most attractive market for South African investment for the same reason other foreign investors have flocked here in recent years -- political and economic security.

The labrynthine path of holding companies and investments that can be traced from Anglo American to Newmont Mining is typical of the roundabout way South African money has been invested in the United States, according to analysts.

"It's almost impossible to sort out all of the ownership," Knight said. "You have that whole interlinking connection. The Anglo companies are all like that."

Although technically Newmont Mining remains an independent company, with more than 50 percent of its stock available to the public, analysts say it is effectively controlled by companies with roots in South Africa -- and has been since Consolidated bought a 26 percent stake in the company in 1981.

Anglo American owns 39 percent of a Bermuda-based holding company, Minerals & Resources Co. (Minorco). A company closely tied to Anglo, De Beers Consolidated Mines Ltd., owns 21 percent of Minorco.

Minorco, in turn, is the umbrella company for many investments in the United States, and was the Anglo American subsidiary that owned stock in Salomon. It has a 57 percent stake in Inspiration Resources, a large American copper producer; 53 percent of Adobe Resources, a New York-based petroleum company, and 30 percent of Engelhard Corp., a large Edison, N.J.-based chemicals and metals concern.

Minorco also owns 28 percent of Consolidated Gold Fields, which owns the 49.7 percent stake in Newmont.

Along the way, these companies have extensive interests in other mining and resources companies in the United States and South Africa. And through Newmont, the South African investors get minority stakes in several South African, Namibian and Australian gold mining companies, Newmont's own U.S. coal and petroleum holdings, and Newmont's 46.5 percent interest in Peabody Holdings, a large American coal producer.

Anglo American, meanwhile, has roots that go even deeper into South Africa. It owns 34 percent of De Beers, a major miner of diamonds and gold, while De Beers owns 38 percent of Anglo. Atop it all, with significant investments in both of those companies, is the Oppenheimer family, a rich South African family whose patriarch, Harry Oppenheimer, is considered a major business power in that nation and the controlling force behind the Anglo American empire.

The links between all of these companies go beyond ownership. Many of them share the same executives and directors, and Newmont's chairman, Gordon Parker, is a South African installed by Consolidated Gold Fields shortly after Consolidated bought 26 percent of Newmont in 1981.

Antiapartheid activists see these apparently tight connections as proof of Anglo American's spreading power. But some analysts disagree, arguing that the effect of the holdings is diluted in each step away from the South African base, and that many of the companies appear to operate independently. "It's a convoluted kind of reasoning to say that Harry Oppenheimer controls Consolidated Gold Fields. I don't think he does," said Warren Myers, an analyst who follows the South African industry for Merrill Lynch & Co.

Many analysts also dispute the activists' contention that Anglo American's increasing grip on Newmont is setting up a stranglehold on the world gold market -- especially with Newmont's recently increased estimates of reserves and production plans.

While that gives Anglo American -- South Africa's No. 2 gold miner -- and its affiliates significant shares in at least two of the world's key gold-producing nations, the analysts point out there still are many other players in gold in South Africa and around the world.

Even its backers concede that the effort to block South African investment in the United States is not nearly as far along as the very successful drive to force American companies to withdraw from South Africa. Leland still is sounding out support for his bill, and Wilson, who handles legislative affairs for the Washington Office on Africa, says the idea of slowing capital flow into the United States for any reason is a hard sell. "People are more alarmed about the Leland language than they are about the disinvestment idea," she said.

Still, Leland and others hope to get some sort of anti-South African investment language included in coming versions of South African economic sanction legislation, and Leland has called for hearings on the subject.

"I fear that Anglo American's quest to gain direct control over Newmont ... raises serious national questions," Leland said in introducing his bill. "It is clear to me that the profits generated in South Africa through the apartheid system are, under our very noses, being invested in the United States capital markets. In turn, there is every opportunity for South African businesses to benefit from the labor or American workers while these same businesses profit from the apartheid system.