The South African government reacted with dismay today to Wednesday's approval by the U.S. House of Representatives of a bill requiring American economic withdrawal from this country.

Describing the vote as "inexplicable," Foreign Minister Roelof F. (Pik) Botha implied that the House had acted irresponsibly, disregarding the effects a total trade cutoff would have on South Africa's neighboring black states.

"It is clear that the American House of Representatives do not give a fig for the black communities of South Africa," Botha said, adding that he was confident the Senate would act "more responsibly" and not pass the bill.

Meanwhile, the first signs of frustration about the state of emergency surfaced today among business leaders worried about the wave of unrest that has hit the country as a result of the detention of hundreds of union leaders.

A group of top businessmen sent a message to Law and Order Minister Louis le Grange today seeking an urgent meeting with him to ask for the release of union leaders so that negotiations on ending a week-old wave of strikes could begin. The meeting is expected to take place Friday.

At least 60 protest strikes have been staged at six major chain stores and business leaders say the action is snowballing. They describe the situation as "chaotic" because, with so many union leaders in detention, there is no one with whom they can try to negotiate an end to the strikes.

The strikes began last Friday shortly after two officials of the powerful Commercial, Catering and Allied Workers' Union were detained. Under the terms of the stringent press restrictions, the officials may not be named.

Botha's response to the House's action came as official spokesmen for the government's Bureau for Information continued to claim that "behind the rhetoric" there was tacit approval in key international circles for South Africa's emergency declaration and large-scale political detentions.

For the second consecutive day, the bureau's director, David Steward, cited the partial recovery of the rand, South Africa's currency -- which has risen to 41.20 U.S. cents from last week's low of 36.55 cents -- as evidence that business confidence at home and abroad had been restored by firm action to end civil unrest.

At the same time, however, there appears to have been a second wave of detentions involving large numbers of union members in the last few days. Several union offices in Johannesburg, including those of the Congress of Unions of South Africa, the main federation of black unions, and the 250,000-member National Union of Mineworkers, have been raided.

The Johannesburg Star reported today that most labor union offices in the city had ceased to function because their leaders were either in detention or in hiding. Those left were afraid to operate from their offices, the newspaper said.

The government refuses to confirm or deny these reports or even to disclose the number of people who have been detained, but the respected Institute of Race Relations which has been trying to monitor the situation, said today it believed more than 3,000 people were now in detention. Earlier this week it gave an estimate of 2,000. Three days after the state of emergency was declared, others estimated the number of detainees varied between 2,000 and 4,000.

According to witnesses, police on two occasions arrested all the workers holding a sit-in demonstration in a store. A store manager who objected to police during one of these incidents is said to have been threatened with arrest.

Businessmen were reluctant to talk about the strikes or their planned meeting with le Grange, reflecting a nervousness that has become pervasive since the sweeping emergency regulations went into effect.

Asked what they would discuss with the minister, Clive Weil, one of those in the delegation replied: "I don't think I can tell you that in terms of the emergency regulations."

One businessman who was prepared to speak out was Anthony Bloom, president of a major industrial conglomerate called the Premier Milling Group. Bloom said he had sent telegrams to le Grange and Manpower Minister Pieter T. du Plessis protesting the detention of union members. He said the detentions would have a devastating effect on industrial relations. Many companies had tried to establish sound relationships with the new black unions, but these were now being undermined.

"Apart from the humanitarian aspects of detention without trial, this will create a legacy of bitterness in the business sector," Bloom said.

In his statement reacting to the bipartisan vote in the House on the sanctions bill, Botha said it was particularly ironic that the House should vote to sever trade ties after South Africa's trade with the rest of Africa had doubled in the past year.

South Africa has a customs union arrangement that provides Swaziland with 61 percent of its total income, Lesotho with 37 percent and Botswana with 32 percent, Botha said.

Furthermore, he said, South Africa provides 99 percent of Lesotho's imports, 90 percent of Swaziland's and 88 percent of Botswana's. South Africa also accounts for 45 percent of all the trade of Malawi, Zimbabwe, Zambia and Zaire.

"I find it inexplicable that a responsible institution of authority such as the American House of Representatives cannot realize that the punitive measures they are imposing may deprive millions of black people of their incomes, and that they will promote poverty and unemployment which in turn will create fertile ground for the enemies of the United States," Botha added.

Meanwhile, severe new restrictions were imposed today in 13 districts of the eastern Cape Province, a black activist stronghold which has been the scene of some of the bloodiest conflicts during the past two years of racial unrest.

The local police chief, Ernest Schnetler, used the sweeping powers of the emergency regulations to declare a 9 p.m. to 4 a.m. curfew in all black townships in the 13 districts.

He also prohibited the wearing of T-shirts bearing the names of 47 black community organizations. Another restriction bars anyone who is not a student -- including the parents of students -- from being on school premises, a move apparently intended to prevent adult "agitators" from meeting with black students.

Strict controls also have been placed on funeral services, which have often been turned into political rallies by the activist organizations. Now, only ordained clergymen are allowed to speak at funerals, and no public address systems may be used. Banners also are prohibited.

Similar funeral restrictions have been proclaimed in five other regions of South Africa.

The Bureau for Information announced at its daily news briefing in Pretoria today that the burned bodies of three people had been found overnight. The incidents brought the death toll since the emergency was declared a week ago to 48, making it one of the bloodiest weeks in several months.

In Cape Town today government officials ordered thousands of black refugees from the Crossroads squatter complex to leave the church halls and mosques where they have been living since their shacks were destroyed in bitter factional fighting over the past month.

The refugees were told they had to leave by Monday and have been warned not to rebuild their shacks on the old sites. The refugees are being forced to move to a new township called Khayelitsha, several miles farther from the city. For the past five years, they have bitterly resisted being moved there.

Several freelance journalists contributed to this report