A wide range of leaders from South Africa's black and white communities reacted with sharp disappointment today to President Pieter W. Botha's refusal to announce new reforms in South Africa's system of white minority rule.

The chorus of dismay and regret was led by both black and white political moderates, some of whom said they felt betrayed by Botha's speech last night in which he insisted he would not bow to continuing black unrest here nor to intensifying foreign pressure to make changes or dismantle the system of racial segregation known as apartheid.

Nobel Peace laureate Desmond Tutu, the Anglican bishop of Johannesburg, said he was "quite devastated" by Botha's speech. Appearing on the brink of tears at a press conference here, Tutu said that following the address, "I think the chances of peaceful change are virtually nil . . . We are going to need a major miracle."

Black leaders normally supportive of the government bitterly assailed the speech, including Lennox Sebe, president of the nominally independent black "homeland" of Ciskei, who accused Botha of "betraying" black community leaders such as himself. Tom Boya, mayor of the township of Daveytown outside Johannesburg, said he was "terribly disappointed" by Botha's remarks.

Business Day, a major English-language daily that reflects the views of the white corporate community here, called for Botha's resignation.

"With the eyes of the world on him, he behaved like a hick politician," a front-page editorial said. "He made a mockery of the support that he has received from the business community. He has made fools of our friends abroad."

Reflecting the lack of confidence of the business community, the country's financial markets were in turmoil today. The rand, South Africa's currency, plunged 6 cents on the Johannesburg foreign exchange market to its lowest level in memory, 38.5 U.S. cents, before recovering slightly to 40.5 cents later in the day, and slid sharply against all other major currencies. A year ago the rand was worth 65 U.S. cents.

Botha's speech had followed broad public hints and background briefings from officials who had promised significant new measures, few of which were even mentioned by Botha last night. Informed South African analysts said they believed the president had been angered by this week's press reports and by the buildup of expectations and had decided to delete announcement of the new steps so as not to appear to be yielding to such pressures.

He also announced no changes in the state of emergency he declared four weeks ago to deal with unrest that has claimed more than 600 lives in the past year.

Botha was all smiles this morning at a breakfast meeting of ruling party members in Durban, expressing amusement over what he called "the confusion of Babel over my speech."

"Give them time to study the speech," he said, referring to his critics. "Apparently some have slept badly last night."

Tutu said the president had "fluffed" an opportunity to go down in South African history as a great statesman, behaving instead "like a hack politician pandering to the least informed and most racist" of his ruling party's constituents.

Tutu said he would consider calling for immediate international sanctions against South Africa -- an illegal act under South African law that could result in a five-year jail sentence -- instead of his previous stance that foreign nations should hold off for 18 months to two years to give the government here time to institute change. He also said he saw little point in joining Monday's scheduled meeting between Botha and a delegation of Anglican clerics to discuss black unrest and the government's four-week-old state of emergency.

Tutu said blacks in general had not expected "a great deal" from Botha, but had been given "no hope" by his speech.

Fellow Anglican Bishop Simeon Nkoane of the black township of Kwathema, who along with Tutu saved the life of an alleged police informer from an angry mob last month, said the speech left him "bruised and spiritually devastated."

"For many days to come I shall not have the courage to look a white friend in the face, nor to speak nor smile with anyone who is black and young," said Nkoane. "My heart bleeds for the youths of our townships."

Two of the country's largest business associations, whose leaders have given cautious support to Botha's emergency decree, expressed "regret" that Botha had not been "more specific" about his plans for the country's future. The presidents of the Federated Chamber of Industries and the Afrikaner Institute of Commerce called for "practical steps . . . in particular through a visible process of negotiation with all black leaders in South Africa."

But it was those blacks most closely identified with the white-ruled government who appeared most bitter over Botha's tough stance, saying he had undercut their efforts to convince the black population that political moderation and cooperation with whites were still viable options.

Ciskei's Sebe said at a press conference that he had been misled by Foreign Minister Roelof F. Botha at a recent meeting in which Botha, who is no relation to President Botha, had discussed likely steps to be announced.

President Botha "sent his foreign minister all over the world, including my own office, on a briefing mission to raise expectations," said Sebe. "When the moment of truth arrived, not even one of the most moderate expectations were met."

The foreign minister later denied allegations that he had misled foreign leaders and fueled the high expectations about the president's speech.

Daveyton's Mayor Boya, who earlier had said he was hoping for a major shift in policy from Botha, said the speech would make "much more difficult" the position of himself and other black moderates.

New incidents of unrest were reported today in black townships in the Johannesburg, eastern Transvaal, and eastern and western Cape regions, athough no new deaths were reported. Police also announced that they had arrested 40 more persons using their broad emergency powers, bringing to 1,753 the number detained since the decree took effect. They reported that 1,024 of those detained have been released.