HAVANA -- Fidel Castro yesterday signaled that he is itching for a return to public life after eight months of illness that has kept him out of sight, lambasting U.S. biofuel policies in a front-page newspaper editorial.

But Mr. Castro's scathing attack in the Communist Party daily left unanswered what role he will play in politics and government, and when he might appear again in public.

In his article, the 80-year-old revolutionary asserted that President Bush's support for using crops to produce ethanol for cars could deplete corn and other food stocks in developing nations, putting the lives of 3 billion people at risk worldwide.

"There are many other issues to be dealt with," Mr. Castro added at the end of the editorial, apparently promising more such missives.

Unlike several other written messages signed by Mr. Castro since he fell ill, this one did not seem aimed at dispelling rumors about his health and didn't even mention that he has been sick.

"This shows a more aware and lucid Mr. Castro than that suggested by the wan pictures we've seen over the past few months," said Cuba specialist Wayne Smith, who served as the top U.S. diplomat in Havana from 1979 to 1982. "My own take is that this does not presage some early return to power," he said. "Rather, it is a matter of Mr. Castro wanting to get his two cents in about a subject he cares much about."

Mr. Castro's future role has been the source of much speculation -- especially in the past few months, amid increasingly optimistic reports from senior Cuban officials and family members about his recovery. Mr. Castro's condition and exact ailment remain a state secret, but he is widely believed to suffer from diverticular disease, a weakening of the walls of the colon that can cause sustained bleeding.

While some seem confident that he will resume the presidential role he temporarily ceded July 31 to his brother Raul, others think it more likely that he will take on a less physically demanding post as elder statesman, weighing in on international issues while his brother and a new collective leadership handle domestic affairs.

Mr. Castro "no longer has the physical capacity to sustain his previous activity," said Manuel Cuesta Morua, a center-left Cuban intellectual and dissident. Before he fell ill, Mr. Castro was famous for his exhausting schedule, often staying up all night to entertain visiting foreign leaders and speaking extemporaneously on live television for hours.

Mr. Castro ceded his presidential functions to his 75-year-old brother, the defense minister, as he disclosed that he had undergone emergency intestinal surgery. He has not appeared in public since. In the meantime, Raul Castro has run the nation at the head of a collective leadership named by his older brother.

But it was clear from his article that Fidel Castro now wants his voice to be heard on international issues, especially when it comes to the environment.

Written in the same apocalyptic tone that Mr. Castro has adopted in the past to discuss the effects of U.S. policies on developing nations, there was no reason to doubt that he was the author.

"The sinister idea of converting food into combustible was definitively established as the economic line of the foreign policy of the United States," Mr. Castro wrote of Mr. Bush's discussions of biofuels with U.S. automakers this week.

He noted that Cuba has also experimented with extracting ethanol from sugar cane, but said there could be disastrous consequences if rich nations imported key food crops such as corn from poor countries to help meet energy needs. "Apply this recipe to the countries of the Third World, and you will see how many people among the hungry masses of our planet will no longer consume corn," the article said.