Dec. 18 (Bloomberg) -- Fidel Castro hinted he may step down as president of Cuba, saying that his duty wasn't to ``cling'' to office or to stand in the way of younger people.

The ailing leader, 81, who hasn't been seen in public since undergoing surgery for intestinal bleeding in July last year, made the comments in a letter sent to Cuban television's ``Round Table'' program, and Cuban radio. The text was published on the Web site of Granma, the official Communist party daily.

``My basic duty isn't to cling to office, or much less to obstruct the passage of younger people,'' Castro wrote. ``Rather it is to bring experience and ideas whose modest value comes from the exceptional era in which I happened to live.''

Castro handed temporary power to his brother Raul last year and has since appeared in footage and photos with Venezuelan President Hugo Chavez. Castro's lack of public appearances has prompted speculation about whether he would return to power, though he was this month nominated to Cuba's National Assembly, where he needs to hold a seat if he is to remain president.

The dictator also said that he thought he should be ``consistent'' until the end, like the Brazilian architect Oscar Niemeyer, who turned 100 last week, and about whom Castro once said ``Niemeyer and I are the last Communists on the planet.''

The bulk of Castro's letter, dated yesterday, referred to climate change and the agreement reached last week in Bali, Indonesia, by world governments to embark on two years of talks leading to the signing of a new treaty to fight global warming.

U.S. `Obstruction'

Castro criticized the ``tenacious obstruction'' of the U.S. in the Bali talks, and said the world's biggest economy ``maneuvered to avoid its isolation, although it didn't change at all the dark intentions of the empire.''

The U.S. on the final day of the two-week conference switched from opposition to a compromise text, to acceptance of its contents, after being criticized by delegates from nations including South Africa and Papua New Guinea.

Castro characterized the climate change negotiations as a gathering in which developing nations ``are fighting for their development and are calling for an equitable treatment, financial resources and the transfer of technology from representatives of industrialized nations.''

To contact the reporter on this story: Alex Morales in London at amorales2@bloomberg.net.

Last Updated: December 18, 2007 05:31 EST