LUSAKA, ZAMBIA, NOV. 1 -- One of Africa's most well-known and longest-serving presidents, Kenneth Kaunda, suffered a crushing defeat today in Zambia's first multi-party elections in two decades, marking the first time in English-speaking Africa that an entrenched one-party system has been smashed at the ballot box.

News of the defeat of Kaunda, who has ruled for 27 years, set off wild celebrations in the capital with cars and trucks full of Zambians honking their horns and chanting the opposition slogan, "The hour has come."

Kaunda, 67, who guided Zambia to independence from Britain in 1964 and led the campaign for international isolation of South Africa, conceded defeat tonight in a telephone call to his opponent, Frederick Chiluba. By then, international election monitors, including former president Jimmy Carter, had confirmed that an overwhelming opposition victory was inevitable.

Chiluba, a former trade union leader, captured 81 percent of the vote for president, according to the latest partial returns. In separate balloting for the 150-seat legislature, Chiluba's opposition Movement for Multi-Party Democracy (MMD) won nearly 90 percent of the vote.

By ending the reign of one of the key figures identified with Africa's independence era nearly three decades ago, the elections thrust Zambia to the forefront of the process of democratization transforming the way much of Africa is governed. Over the past two years, popular movements demanding political pluralism and economic change have swept aside more than a dozen single-party governments of often unaccountable and harsh rulers.

Kaunda "promised to cooperate with us," Chiluba told a news conference after talking to the president tonight. "He is ready to move out of State House {the presidential palace}, but we are not chasing him." Carter told the Associated Press that the swearing-in ceremony will take place Saturday.

Chiluba called on Kaunda to remain in the country and help rebuild it. "I want the fears to vanish, to disappear from his mind," he said. "There will be no witch hunting. Kenneth Kaunda is the father of this country, so we must show him respect."

Kaunda's ruling United National Independence Party (UNIP) agreed in September to hold elections after Chiluba's opposition movement mounted an intense, 18-month campaign that featured rallies of hundreds of thousands of Zambians demanding a return to multi-party politics.

"The people were longing for this for a very long time, and when they got the opportunity, they took it," Chiluba said in an interview earlier today after the scale of his victory became apparent. "Before this movement began, I never really thought about becoming president. I was just working for freedom for my people -- in politics, in economics and in religion."

Kaunda declared a one-party state in 1973, citing the need to thwart the rise of tribalism.

Since forming his opposition party in December 1989, Chiluba has ridden atop a rising wave of popular discontent with Kaunda's increasingly autocratic government that is widely blamed for leading Zambia from being one of Africa's richest nations at independence to economic ruin.

Kaunda's legacy will leave the incoming Chiluba government with a daunting task to rebuild an economy saddled with a more than $7 billion foreign debt, a failing agricultural sector, dwindling copper reserves, crumbling infrastructure and widespread unemployment.

Chiluba credited the international observers, including a team headed by Carter and another from the Commonwealth, for giving Zambians confidence that Thursday's balloting would be free and fair. Chiluba vowed to quickly lift the 27-year-old state of emergency but refused to be precise, saying, "It could be six days, six weeks or six months."

Chiluba, 48, former chairman of the Zambia Congress of Trade Unions, was detained under the state of emergency in 1981 and harassed throughout much of the decade.

Since he launched the MMD, Chiluba capitalized on the popular desire for one thing Kaunda could not deliver: change in political leadership. A deeply religious man, Chiluba campaigned on a platform of free enterprise and human rights.

Celebrations were well underway this afternoon in the impoverished townships around Lusaka. At the Kalingalinga township, shouts of "He's gone, he's gone" and "The hour has come" erupted from a crowd of men gathered at a local beer hall as the national radio announced partial election results.

"Twenty-seven years is too long," Edward Mwanza, 30, yelled over the din. "People were just tired of a one-man show. We wanted change."

In many ways, it was in Kalingalinga that Kaunda's one-party state began to unravel 15 months ago. It started when the government raised prices for the nation's staple, cornmeal. Students from the University of Zambia, just 500 yards from the township, marched into Kalingalinga in June last year and together with local residents began looting state-owned shops. The ensuing rioting which spread to the rest of Lusaka, and marked the first time that students and unemployed young people had joined forces.

"Those riots were the beginning of the end for Kaunda," said Robinson Makayi, editor of the independent Weekly Post. "Kaunda did not know it then, but power was reverting to the people."

On June 30, 1990, a lone soldier briefly occupied the national radio station and announced Kaunda's ouster. People poured into the streets, singing and dancing for several hours until the security forces restored order.

From then on, the MMD and Chiluba grew rapidly in strength, forcing the government into repeated concessions. A new constitution was written, the High Court forced the state-controlled media to broadcast opposition views, and all political detainees were released.

"We Zambians could just not take it anymore," said Steven Phiri, a 46-year-old bricklayer in Kalingalinga. "The old man just had to go."