CUBA — Cubans have been warned to prepare for tough times ahead as the island becomes the latest victim of the global economic downturn.

President Raul Castro used a speech on Saturday to mark the 55th anniversary of the communist uprising to warn that rising fuel and food prices would take their toll on the nation.

“We must bear in mind that we are living in the midst of a true world crisis that is not only economic but also related to climate change, the irrational use of energy, and a great number of other problems,” he said.

Mr. Castro, 77, who officially took over from his ailing brother, Fidel, 81, in February, had been expected to use the speech on Cuba’s national holiday to announce changes to economic policy but instead chose to prepare his people for difficulties ahead.

“Regardless of our great wishes to solve every problem, we cannot spend in excess of what we have,” he told a crowd of 10,000 in Santiago de Cuba, the island’s second city.

But he said Cuba would continue to build its defences against any threatened invasion by America.

“Preparations to defend the country are going well,” Mr. Castro said. “We shall continue paying special attention to defense, regardless of the results of the next presidential elections in the United States.”

The Rebellion Day celebrations two years ago were the last public event at which Fidel Castro was seen before he underwent emergency intestinal surgery from which he has never fully recovered.

Since taking over, the younger Mr. Castro has eased restrictions and vowed to change the egalitarian wage system. However, opponents dismiss the reforms as “cosmetic.”