The governor of South Africa's central bank accused a handful of American banks yesterday of triggering his country's debt crisis. He then flew to London in hopes of getting European cooperation in rescheduling South Africa's international loans.

In the first full public statement on his emergency mission through western financial capitals, Gerhard de Kock said South Africa's freeze on debt repayments was forced by just two or three American banks refusing to renew maturing loans.

"Two or three intimated that their exposure to South Africa was too large," de Kock told a hastily arranged news conference in New York, where he explained that the American withdrawal had sparked fears that other banks would follow suit.

Although de Kock blamed American banks for precipitating his country's debt crisis, the picture is far from clear. Senior American banking sources familiar with the de Kock mission said the governor had spoken privately of a gradual withdrawal by both European and American banks from South Africa during the past 12 months.

This gradual erosion of credit to South Africa had been a cause of major concern to the South Afreican Reserve Bank, although confidence snapped after a report in early August that Chase Manhattan Bank was severing its credit lines to private borrowers in South Africa. "That may have been the cause of panic," said one senior banker familiar with South Africa. "But it is not true that the Americans were the only ones pulling out of South Africa."

As de Kock spoke, the white-minority government in Pretoria faced a renewed run on the rand, which dropped nearly 5 cents, from 41.5 cents to 37 cents against the dollar, in early trading. The rand later recovered to 38.8 cents after the central bank intervened by selling some of its scarce dollars.

The rand's volatility, in the wake of Monday's reopening of the foreign exchange markets, could mean that South Africa's foreign debts, which are figured in dollars, will be more expensive to retire.

At his news conference, de Kock declined to identify the American banks that had reduced their exposure, but he said their action had political motives and added: "Two are definitely out, and a third is on the fence."

In the banking community, American banks are widely seen to be under more pressure from public opinion than the Europeans to reduce their lending to South Africa, a point underlined by de Kock, who said that European banks "have given no indication of not rolling over their credit to South Africa."

South Africa has about $6 billion in interbank and trade-credit lines, on which maturities normally range from overnight to 30 days. Of that, about $2 billion is held by American banks; overall, South Africa's short-term debt is $12 billion, maturing within the next 12 months.

"No country can repay all of its short-term liabilities in three months, so we were forced to the decision of rescheduling our debt," the governor said. "We will continue to repay all interest payments and, if the American banks insist on withdrawing from South Africa, we will repay all money eventually -- not in three months, but eventually."

In banking circles, this was interpreted as a veiled warning to American banks that the beleaguered South Africans could play tough if the banks refused to negotiate a rescheduling agreement. "They don't have that many cards to play, but there is a danger in allowing them to impose rescheduling terms unilaterally," said one banking source.

De Kock said his next step was to set up a working party to arrange rescheduling terms for the $12 billion in short-term debt that falls due within the next 12 months. He said he hoped to appoint an investment bank or a senior international banker to coordinate the effort. Bankers said, however, that it would be extremely difficult to find a banker who is not personally involved, because South Africa has such a wide debt exposure to international banks.

One informed source in the Reagan administration said that London-based Barclays Bank, which has a high exposure through its South African associate, Barnat, had been asked to lead negotiations on behalf of international creditors but had declined. Barclays refused to comment yesterday.

De Kock refused to say yesterday whether American banks were willing to cooperate in a rescheduling agreement involving what he called a "standstill" between South Africa and her international creditors. "Moratorium," he said, employing the term more widely used to describe South Africa's situtation, "sounds more like crematorium."