By Jeff Franks
HAVANA (Reuters) - Cuban President Raul Castro turned 79 on Thursday, showing no signs of slowing down as he works to assure that Cuban communism survives beyond his generation.
His birthday was not mentioned in Cuba's state-run newspapers, possibly because the topic is a sensitive one for the country's ageing leaders.
They have no obvious younger successors, but Castro, who replaced ailing older brother Fidel Castro in February 2008, appears to be in good health and in no mind to leave office anytime soon.
While opponents in the United States and elsewhere have long said the system installed after Cuba's 1959 revolution would die with the Castros, Raul Castro has made clear that he plans to keep Cuba communist long after he and his brother are gone.
"There are those in U.S. ruling circles who say they will wait for the disappearance of the revolution's historic generation, a sinister bet on the so-called 'biological factor,' or the death of Fidel and all of us," he said in speech to Cuba's National Assembly in August.
"Those who think like that are doomed to failure."
Cuban leaders are at work on "the ongoing upgrading of our economic model in order to set the foundations of the irreversibility of Cuban socialism," Castro told the Young Communist League in April.
The task is not easy because it is a fight against time and a powerful inertia that has settled over the Cuban system through its five decades of existence.
Castro, the former defence minister, has tried to tackle the latter by filling many positions in the Council of Ministers, effectively his cabinet, with military men whom he trusts to follow his orders.
He has made a number of tweaks to the economic system with the aim of providing financial incentives for harder work while at the same time modestly reducing the state's role.
LARGER REFORMS
So far, the known changes include mostly small but symbolically important things such as allowing barbers and bus and taxi drivers to operate more like their own small businesses, and giving private farmers and cooperatives greater freedom from reliance on the government.
But larger reforms in the retail and service sectors are being hinted at in public discussions in state media, and perhaps in Castro's private conversations.
Venezuelan President Hugo Chavez, Cuba's closest ally, said on Venezuelan television last week that Castro confided to him -- as a warning not to do the same thing -- that Cuba had "committed many errors" in its development of communism.
Chavez quoted Castro as saying: "Here we nationalized even the funeral home, the barber shop, the sale of ice cream. That doesn't have any reason to belong to the state."
Castro also has launched a crackdown on corruption and said Cubans must become less dependent on government handouts.
"What we are seeing is that Raul Castro is much more pragmatic than Fidel. What remains to be seen is how far he will go with his reforms and whether they will be sufficient," said a western diplomat based in Havana.
Castro has spoken about future leaders only in general terms, saying in speeches there are many young Cubans who will maintain the revolution in coming years.
But time is becoming a precious commodity for the country's leaders.
Castro's immediate successor, first vice president Jose Ramon Machado Ventura, will turn 80 in October and the average age of all six vice presidents on the Council of State is 71.6 years.
They are all younger than Fidel Castro, who is 83 and has not appeared in public since undergoing intestinal surgery in 2006, but remains the head of the party.
Speculation on who will lead once this generation is gone ranges from younger members of the Castro family to younger military men now in high positions.
"But there are no obvious candidates, nor any who are clearly being groomed," said another western diplomat.
The two men thought to be the most likely younger successors, former Vice President Carlos Lage and former Foreign Minister Felipe Perez Roque, were dismissed in a cabinet shake-up last year after they were secretly taped speaking ill of their elderly bosses and hinting at changes to come.
(Editing by Mohammad Zargham)