HAVANA - Former Cuban leader Fidel Castro dampened hopes of a thaw in chilly ties with Washington Wednesday by saying President Barack Obama "misinterpreted" apparently conciliatory words by his brother Raul.

Obama and Cuban President Raul Castro said recently they were willing to open talks on such hot-button issues as political prisoners and human rights, with Castro saying "we are open, whenever they want, to discussing everything."

But Fidel Castro, writing in an article posted on the official website CubaDebate, said that "without a doubt, the president misinterpreted Raul's statement."

Fidel Castro, 82, clarified that any liberation of 75 jailed opponents to Havana's regime would come only if the United States is "willing" to release five Cubans detained on espionage charges.

Raul Castro's words were meant to show "courage and confidence in the principles of the revolution," wrote Fidel, who was forced to hand the presidency to his brother after a gastrointestinal operation in 2006.

Obama last week said he wanted to establish "a new beginning" with Cuba, while Secretary of State Hillary Clinton called Raul Castro's remarks "a very welcome overture" and directly acknowledged for the first time that US policy toward Cuba had failed.

But just as hopes rose that 50 years of Cold War bad blood might become a thing of the past, Obama cautioned that US policy -- namely the 47-year-old full economic embargo on the communist-run island -- would not be changed soon.

"The issues of political prisoners, freedom of speech and democracy are important, and can't simply be brushed aside," he said at the close of an Americas summit in Trinidad and Tobago at the weekend.

On Monday in another article on CubaDebate, Fidel Castro urged Obama to end the US economic "blockade" of Cuba. On Wednesday he lamented that Obama expressed support for keeping the embargo in place.

"He did not invent it, but he made it his own just like 10 other presidents of the United States," Castro said.

"You can predict certain failure for him on that road, just as for all his predecessors," Castro said.