The 77-year-old president also warned of tough challenges ahead, with Cuba hard hit by the global economic crisis and the aftermath of three hurricanes this year that left some 10 billion dollars in damage.

Despite high hopes for improved relations with Cuba's northern neighbour and decades-long foe after the US election of Barack Obama, Raul Castro warned future leaders against softening toward "the enemy."

"One after the other, all the North American administrations have ceaselessly tried to force regime change in Cuba," Castro said in a speech in Santiago de Cuba, the city where Fidel proclaimed victory over US-backed dictator Fulgencio Batista in 1959 after 25 months of fighting in the Sierra Maestra mountains.

"Resisting has been the pledge and the key of each of our victories during this half-century of tough fighting," said Raul, who officially took over from 82-year-old Fidel last February.

Fidel, who has not appeared in public since undergoing major surgery almost two and a half years ago, sent a brief, signed greeting to the Cuban people in Granma, the Communist Party newspaper.