PHILADELPHIA, Aug 1 (Reuters)--Deep divisions over whether to maintain a four-decade-old U.S. trade embargo against Cuba surfaced this week among Republicans at their national convention to nominate Texas Gov. George W. Bush for the White House.

While the Republican platform reaffirmed a hardline stance on continuing the embargo against Cuban President Fidel Castro's communist government, respected Republican voices said it should be lifted.

Former Republican Secretaries of State George Shultz and Lawrence Eagleburger called on Monday for an end to the embargo at a foreign policy forum, saying Cuba had ceased to be a threat after the collapse of the Soviet Union.

"Personally, I would end the embargo," said Shultz, who headed the State Department under former President Ronald Reagan.

Critics of the embargo say it is a relic of the Cold War that has failed to oust Castro and given him an excuse for his country's hobbled economy.

The Republicans' pro-embargo plank says the embargo should not only stay in place until Castro frees political prisoners and allows free speech, but calls for U.S. support for Cuban internal opposition, along the lines of Reagan's backing of Polish dissidents two decades ago.

Shultz and Eagleburger, who was secretary of state under former President George Bush, were among prominent Republicans, including a third former secretary of state, Henry Kissinger, who called two years ago for a national commission to review Cuba policy. The Clinton administration preferred not to open the politically sensitive issue.

Rift Reflects Congressional Debate

The rift among Republicans reflects the debate in Congress over proposals to allow food and medicine sales to Cuba for which U.S. farmers and the pharmaceutical industry have been lobbying.

Softening the embargo has won increasing adherents among Republican legislators from farm states, where farmers hurt by low prices are eager to get into the Cuban market.

But the party stuck to the embargo in its platform for the Nov. 7 election, in which a key state will be Florida, home to a vocal anti-Castro exile community smarting from its defeat over Elian Gonzalez, the 6-year-old shipwreck survivor sent back to Cuba in June after a seven-month international custody battle.

"Our economic and political relations will change when the Cuban regime frees all prisoners of conscience, legalises peaceful protest, allows opposition political activity, permits free expression and commits to democratic elections," said the party platform adopted on Monday.

Support for Dissidents

"This policy will be supported by active American support for Cuban dissidents," the document added.

The party also called for the continued transmission to Cuba of "objective and uncensored news" by U.S. government- funded radio and television stations.

Cuban-American legislators celebrated the party line.

"It was important to reaffirm the embargo policy at this moment when there are so many pressures from economic interests to normalise relations with the dictatorship," said Florida Republican Representative Lincoln Diaz-Balart.

The congressman said anti-embargo comments by Shultz and Eagleburger were not new.

"It is unfortunate, but it is no surprise. They represent big economic interests that want to do business with Castro in a slave economy," he told Reuters.

The Republican platform called for compliance with the 1966 Cuban Adjustment Act, which protects "the rights of Cuban refugees fleeing Communist tyranny."

Under immigration accords reached with Havana by the Clinton administration, Cuban rafters intercepted in the Florida Straits are sent back to Cuba, a policy that roils exiles in Miami.

"A Bush administration would be prepared to break the migration pact," Diaz-Balart said. "There'll be a re-evaluation of Clinton's repatriation policy.'