The former president, 89, acknowledged his advanced age but said Cuban communist concepts were still valid and the Cuban people "will be victorious".

It was earlier announced that Cuba`s President, Raul Castro, would remain party chief for another five years.

Raul Castro, who himself is 84, is due to step down as president in 2018.

But in Cuba the role of Party secretary is considered just as powerful as president, so his announcement that he had been re-elected for another five years was significant.

Some have interpreted Fidel Castro`s speech as a goodbye to the Cuban Communist Party faithful. Whether he intended it to be is another matter, but it certainly contained references to his own mortality not previously heard from him.

"I`ll soon be 90" the former president told the congress, "something I`d never imagined." His longevity wasn`t through effort, he said, but was rather "a whim of fate".

"Soon I`ll be like all the others," he said, "to all our turn must come." State television showed at least one person in the audience of loyalists wiping tears from their eyes.

But being Fidel Castro, any admission of fallibility or weakness was immediately followed by a statement of defiance: "The ideas of Cuban Communists will remain as proof on this planet that if they are worked at with fervour and dignity, they can produce the material and cultural goods that human beings need."

Fidel Castro`s speech at the five-yearly congress has been interpreted by some analysts as valedictory, but the Castro dominance in Cuban politics looks set to continue for some time yet.

Raul Castro proposed at the weekend that 60 should become the maximum age for joining the Party`s central committee. Cuba has an ageing leadership - Mr Castro`s deputy in the Party, Jose Ramon Machado Ventura, is 85.

But he also said that there should be a five-year transition period before that comes into force.

He will continue as Party leader until 2021, a move which the BBC`s correspondent in Cuba, Will Grant, says will disappoint many Cubans who had hoped that the recent thaw in relations with Washington might also usher in a new generation of reformers in the Communist Party.

More about: