In an unprecedented, hour-long television address to the Cuban people Tuesday, Jimmy Carter Tuesday night called for an end to four decades of American trade sanctions against the Caribbean communist island. 

"My hope is that the Congress will soon act to permit unrestricted travel between the United States and Cuba, establish open trading relationships, and repeal the embargo," Carter said. 

"Our two nations have been trapped in a destructive state of belligerence for 42 years, and it is time for us to change our relationship," he added. 

Speaking in Spanish in the uncensored broadcast, the former American president also told Cubans of a fledgling democracy effort underway in their communist country and addressed human-rights concerns. 

Democracy, Carter told viewers in heavily accented Spanish, "is based on some simple premises: 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 non-governmental groups and to have fair and open trials." 

In Washington, President Bush urged islanders to "demand freedom" from Cuban President Fidel Castro. 

Bush said of Carter's trip: "It doesn't complicate my foreign policy because I haven't changed my foreign policy — and that is Fidel Castro is a dictator and he is oppressive and he ought to have free elections and he ought to have a free press and he ought to free his prisoners and he ought to encourage free enterprise." 

Carter contradicted administration statements Monday, saying he had been told by administration officials that the United States had no evidence the communist country was transferring scientific knowledge that could be used for terrorism. 

The White House on Tuesday reaffirmed its contention that Cuba has given "rogue nations" biological and chemical technology and information. 

The speech by Carter, the highest-ranking American to visit Cuba since its 1959 revolution, amounted to a carefully balanced appeal for America to drop its embargo, and for Cuba to join the democracies of the Western Hemisphere. 

"We hope that someday soon, you can reach across the great divide that separates our two countries and say, 'We are ready to join the community of democracies,'" Carter said. 

"And I hope that Americans will soon open our arms to you and say, 'We welcome you as our friends.'" 

Perhaps the most significant moment in Carter's prepared text dealt with the Varela Project, a campaign to demand changes in the socialist system that governs Cuba's 11 million people. It is not discussed in the state-controlled media. 

For many Cubans, it was the first time they had heard of the project and its discussion drew obvious discomfort in this closed society, where people are unaccustomed to such a public airing of opinions that differ from their government's. 

"I respect his opinions," said one viewer, 50-year-old secretary Graciela Rodriguez. "This gentleman was president and is convinced of his ideas. But he is not Cuban." 

Some seemed more at ease talking about Carter's hopeful words on improving relations. 

"On the day that relations between our countries are normalized, Cuba should thank Carter" said Gisela Frances, a 36-year-old office worker. "He has planted an important little seed." 

Cuca Gomez, a 73-year-old retiree, said she also liked Carter's talk about the two countries becoming friends "and Cuba and the United States resolving their problems." 

Carter's speech "was excellent," said housewife Landolina Tenerero, 57. "He's the only one who has spoken correctly about things here." Asked if that could mean change, she said, "anything can happen here." 

Project Varela backers were delighted. 

Carter's speech "surpassed our expectations," said veteran activist Elizardo Sanchez. For fellow project coordinator Oswaldo Paya, Carter's mention of the effort "means solidarity and public recognition." 

Speaking before a gathering that included Castro and other top officials, Carter said he had been told that the Varela Project "has gathered sufficient signatures and has presented such a petition to the National Assembly." 

Organizers have delivered to the National Assembly 11,020 signatures seeking a referendum that would ask Cubans if they favor human rights, electoral reform, an amnesty for political prisoners and the right to have a business. 

The project is named for the Rev. Felix Varela, a Roman Catholic priest and revered independence hero whose remains are kept in an urn in the University of Havana's elegant Aula Magna, or great hall. It was there, at a wooden podium, that Carter delivered his prepared speech. 

Cuban authorities claim the campaign was "imported" from the United States. The organizers insist it's homegrown, with moral — but not financial — support from abroad. 

"When Cubans exercise this freedom to change laws peacefully by a direct vote, the world will see that Cubans, and not foreigners, will decide the future of this country," said Carter. 

Francisco Cordero, a 37-year-old industrial worker, grinned as he said that Carter's speech was "very good." He said he agreed with Carter's call for better relations with the United States. Asked about the Varela project, he added, tersely, "The same." 

Carter also responded to questions from audience members who defended Cuba's system. 

Hassan Perez, president of the National Student's Union, said he felt "profound indignation" at mention of the Varela Project, and said that its supporters had no support. 

"I would like to see maybe a referendum held and the people of Cuba agree with the 10,000 citizens or disagree," Carter said. "I think the world would look on with admiration." 

Carter also said it was time "to change our relationship and the way we think and talk about each other. Because the United States is the most powerful nation, we should take the first step." 

Reminding his audience of how he normalized relations with China in 1979, he said the United States should lift the 43-year-old embargo on travel to and trade with Cuba. Cuban exiles in America could, he said, serve as "a bridge of reconciliation between Cuba and the United States." 

But he also painted a picture of how the Western Hemisphere had been transformed since the end of the Cold War. 

"When I became president, there were only two democracies in South America, and one in Central America. Today, almost every country in the Americas is a democracy. ... Today, any regime that takes power by unconstitutional means will be ostracized, as was shown in the rejection of the Venezuelan coup last month." 

Carter — who traveled here with official permission from the U.S. government, which licenses all American travel to Cuba — did not spare his own country, pointing to America's large prison population, inequalities in applying the death penalty, and the shortcomings of health care. 

"Still, guaranteed civil liberties offer every citizen an opportunity to change these laws," he said, while "Cuba has adopted a socialist government where one political party dominates, and people are not permitted to organize any opposition movements. Your constitution recognizes freedom of speech and association, but other laws deny these freedoms to those who disagree with the government." 

Outlining his vision for the future, Carter said he wanted freedom of travel and trade, and "a massive student exchange between our universities. I want the people of the United States and Cuba to share more than a love of baseball and wonderful music. I want us to be friends, and to respect each other." 

After the speech, Carter attended a baseball game throwing out the first pitch for the matchup between all-star teams comprised of top players from eastern and western Cuba. Castro also showed up, wearing a baseball uniform and pretending to coach him from the mound. 

Castro, who invited Carter to visit his country, told him on his arrival Sunday that he was free to travel anywhere and talk to anyone he likes. 

"We shall not take offense at any contact you may wish to make," Castro said. 

Less than 24 hours later, Carter met with Project Varela organizers at his hotel and was briefed on human rights and political prisoners in Cuba. 

The Associated Press contributed to this report.