U.S. attitudes toward racial separation in South Africa have never won much applause from either blacks or whites here. Now there are signs of growing hostility and disillusionment in both groups toward the American position.

Whites believe Washington's policies are based on an expedient attempt to win favor in the Third World and to be rid of a potential "flash-point" for superpower conflict. To them, U.S. policies spell the end of white rule -- and whites -- in southern Africa.

South African whites perceive that the official U.S. position of "full political participation" for everyone in this country means loss of political control by the white minority.

For blacks, it is a case of the U.S. government's not putting its money where its mouth is. They see the United States as failing to take logical steps to economically isolate and weaken the white government, which would hasten eventual black rule. American trade and investment in South Africa are seen by blacks as extensions of U.S. government policy.

Official white perspectives on the U.S. role in South Africa recently were set out by a government commission studying press reporting on defense matters. In its final report in April, which heavily on testimony from South African military intelligence, the commission found the United Satates to be as much a danger to the South African government as the Soviet Union.

The white establishment's distrust of U.S. officials resulting from U.S. criticism of apartheid has been increased over the last two years by some clumsy U.S. intelligence attempts to investigate South Africa's nuclear program and by Washington's occasionally inept handling of negotiations on the Pretoria-run territory of Nambia (South-West Africa).

By officially discouraging trade, sports cultural and military links, the United States hopes to pressure the government into reforms, the report noted. Activities of U.S. Embassy personnel inside the country, particularly their involvement in labor disputes between American multinational corporations and black workers, also came under fire.

A library run by the American Cultural Center in the black township of Soweto was described as a place where the "dissemination of foreign propaganda and 'information' takes place." Other unnamed "organizations and agents not enjoying diplomatic privileges inside South Africa also execute the official American policy, the report said. American journalists are no doubt among those "agents," according to the report.

These attitudes have prompted close scrutiny by security police of American diplomats and journalists in South Africa. The Soweto library frequently was visited by plainclothes policemen. Diplomats visiting black activists under house arrest or banning order have been followed and questioned. The U.S. Embassy is now checking out reports that car rental firms have been told to inform the security police whenever an American diplomat or journalist rents a car.

A slide show put together by military intelligence told how "certain foreign embassies" and "certain foreign journalists" trying to undermine order inside South Africa were being "watched," according to one person who viewed it.

The white establishment's growing distrust of U.S. officials is not completely without foundation. Awkward U.S. attempts to discover more about South Africa's nuclear program, uneven handling of the three-year-old negotiations on Namibia and U.S. support for "full political participation" for everyone in South Africa have given Pretoria reason to believe that Washington is not on its side.

Meanwhile, black attitudes toward U.S. policy might be summed up by the snapshot of a U.S. senator that hangs over the desk of a black journalist in Johannesburg.

Although the senator is antagonistic to Pretoria, the journalist had inscribed the photo with these words: "The U.S. will continue to turn a blind eye 'cause we lack vision and/or hindsight."

Anti-Americanism also was expressed in a decision last February by the black consciousness Azanian People's ORGANIZATION (AZAPO) to cease contact with U.S. government officials until three conditions were met.

AZAPO demanded that the United States force American companies to divest themselves of South African interests, refrain from using its veto against economic sanctions in the U.N. Security Council and give greater "material assistance" to "your people outside."

A former president of AZAPO, Curtis Nkondo, was voted out of office when it was discovered that he had attended a dinner given by a U.S. Embassy official in Pretoria. A U.S. consular officer Richard Roth, was expelled from a meeting of black students in Soweto.

Young blacks working for the American Cultural Center are accused by their peers of being CIA agents. A visiting black American professor was forbidden entry to a meeting of black students in Soweto. Several young blacks turned down trips to the United States to show their disapproval of U.S. policy.

Hostility toward the United States has hardened in recent years, according to some blacks. "It's different from 1977," said one black teacher.

"Now it is more pervasive . . . and it's more emotional."

"There is a progressive hardening of attitude against the U.S. primarily because President Carter started talking about human rights as the basis for his foreign policy, and Percy Qoboza, a well-known black editor. "But his government showes little concern for this issue in this country."

Black antagonism to the United States also stems from their belief that American is hostile to socialism, and black activists regard socialism as necessary to redistribute wealth in a new economic order.

Finally, U.S. refusal to give money and arms to black exile groups indicates a lack of sympathy for the "armed liberation struggle that many younger blacks believe is required to achieve change here.