Former president Jimmy Carter, in an unprecedented address carried live tonight on state radio and television, urged Cuba to "join the community of democracies" and endorsed the "fundamental right" of Cuban dissidents to seek changes in the country's laws through direct elections.

Outlining his vision of improved relations between the United States and Cuba, Carter also called for the United States to "take the first step" by lifting the four-decade-old economic embargo against President Fidel Castro's Communist nation -- a position he has stated in the past.

"Our two nations have been trapped in a destructive state of belligerence for 42 years," Carter said in his 20-minute address, which he delivered in Spanish. "And it is time for us to change our relationship and the way we think and talk about each other."

As Castro and his top aides watched from the front row of an auditorium at the University of Havana, Carter praised the Varela Project, a petition drive that gathered signatures of more than 11,000 people demanding new freedoms in Cuba. Most Cubans were unaware of the project's existence, as the government had forbidden it mentioned in the state media.

In central Havana tonight, Marta Rodriguez, 38, stood in the doorway of her home and said she thought that Carter's speech could be a turning point in relations between the two countries.

"We have never had a good relationship with the United States," she said. "But maybe now things are going to change."

Tonight's speech was the centerpiece of Carter's five-day visit to Cuba, the first by a current or former U.S. president to this Caribbean island since 1928. Though visiting Cuba in an unofficial capacity, Carter became the most prominent American to directly address the Cuban people on the state-controlled airwaves, and all sides of the emotional debate surrounding Castro's rule were watching to see how Carter would use that pulpit.

As expected, Carter said he hoped the U.S. Congress would "soon act to permit unrestricted travel between the United States and Cuba, establish open trading relationships and repeal the embargo."

Carter said the embargo, which is strongly backed by the Bush administration, is not the cause of Cuba's deep economic problems, as Castro has long claimed. However, Carter said, "the embargo freezes the existing impasse, induces anger and resentment, restricts the freedoms of U.S. citizens, and makes it difficult for us to exchange ideas and respect.

"I did not come here to interfere in Cuba's internal affairs, but to extend a hand of friendship to the Cuban people and to offer a vision of the future for our two countries."

The university audience greeted Carter, 77, with a standing ovation, but sat silently during his speech and responded with polite applause at its conclusion.

Carter proposed creation of a binational commission to discuss property disputes. Many Cubans in the United States still claim ownership rights to property seized during and after Castro's 1959 revolution.

Carter said he wanted to see "a massive student exchange" between the two countries and for Cuba to adopt the democratic changes necessary to join a Free Trade Area of the Americas.

Without directly criticizing Cuba's human rights record, Carter noted that Cuba's socialist system prohibits organized political opposition, and although its constitution recognizes freedom of speech and association, "other laws deny these freedoms to those who disagree with the government."

The Varela Project seeks a national referendum to guarantee freedom of expression and association, amnesty for political prisoners, free elections and the right to private enterprise. It was also mentioned during a question-and-answer period with students after Carter's speech.

Two questions, from a law professor and a law student, were in the form of long attacks -- at least 10 minutes each -- on the project, which Cuban officials have called a plot by Castro's enemies in the United States. Students and professors in the crowds gave the questioners enthusiastic applause.

"The single most important thing he did was to mention the Varela Project," said Dennis Hays, of the anti-Castro Cuban American National Foundation, who praised Carter for telling the Cuban people "for the first time that they are entitled to these rights."

Hundreds of Cuban dissidents, led by Catholic activist Oswaldo Paya, spent more than a year gathering the signatures and delivered them to the National Assembly last week. By law, legislators must consider and vote on any measure brought to them by at least 10,000 registered voters.

Many Cubans had not heard of the project -- named after Felix Varela, a 19th-century Roman Catholic priest and independence activist -- because they get their information almost exclusively from television and radio broadcasts strictly controlled by the government.

In the question-and-answer period, Carter said he and Castro disagreed about the definition of democracy. Carter said his definition was based on the U.N. Universal Declaration of Human Rights: "All citizens are born with the right to choose their own leaders, to define their own destiny, to speak freely, to organize political parties, trade unions and nongovernmental groups, and to have fair and open trials."

Only a handful of the 20 people interviewed on the streets of Havana tonight said they had watched Carter's speech. But almost all of those questioned said they had seen Carter attending a baseball game with Castro after the speech. "It moved me a lot when he arrived in Cuba," said Rebeca Guada, 35. "But I didn't see him tonight."

Lazaro Quinones, 40, said he had heard about Project Varela on his radio when he was listening to the BBC. He said he thought the issues of democracy, human rights and the Varela Project raised by Carter were "something we should look into."

Joaquin Lorenzo, 74, said he was impressed with Carter, although he wasn't sure what to think about the Varela Project, which he had not heard of before. He said Carter said Cubans had signed the petitions but the questioners in the audience said Cubans from Miami were behind it. He said he wasn't sure whom to believe.

"The political propaganda here is so intense," he said.

Castro had no immediate response to Carter's speech. The two men left the auditorium and went together to a baseball game in Havana, in keeping with the cordial atmosphere of Carter's trip. Before the speech, Carter sang along as the University of Havana choir Religion."

During the visit, Carter and Castro have engaged in a gentle exchange of views on the meaning of democracy and human rights.

"In the United States, we believe that it is very important to have absolute freedom of expression and freedom of assembly," Carter told social work students today on the outskirts of Havana.

On Monday evening, he told another group of students that in the United States "we take pride in our freedom to criticize our own government and to change our government when we don't like it, by voting in elections that are contested."

Without mentioning Carter's remarks directly, Castro responded by saying that Cuba was moving toward a "dream of justice, of true liberty, of true democracy, of true human rights."

Carter's speech came a day before a bipartisan group of members of Congress who oppose the embargo plan to call for changes in policy toward Cuba.

"For over 40 years, our policy toward Cuba has yielded no results," said Rep. Jeff Flake (R-Ariz.). "Castro hasn't held free and fair elections, he hasn't improved human rights and he hasn't stopped preaching his hate for democracy and the U.S. It's time to try something new."

President Bush is scheduled to give a speech next week announcing his plans regarding Cuba, after a lengthy review led by Assistant Secretary of State Otto Reich, his top policy adviser on Latin America and a Cuban exile who strongly opposes Castro. Officials expect Bush, who will travel to Miami to outline his program, to endorse more funding and other aid to Castro's enemies inside Cuba.

Cuban President Fidel Castro shows the way as he and Jimmy Carter arrive at a Havana stadium to watch a baseball game. The visit followed a live television broadcast by Carter, in which the former president stressed democracy and human rights.Jimmy Carter, his wife, Rosalynn, and President Fidel Castro walk to the University of Havana, where Carter spoke.