Fidel Castro has dampened expectations of improved ties between Cuba and the United States by saying an apparent olive branch from his brother Raul had been "misinterpreted".
The retired president repeated longstanding criticism of US policy and said the Obama administration's support of the embargo against the island was doomed to fail.
Raul Castro, who succeeded Fidel last year, triggered a diplomatic flurry last week by promising to discuss "everything, everything, everything" with the US, including political prisoners and human rights.
Barack Obama called the comments an "advance" and told a regional summit the US wanted a fresh approach in Latin America. Days before Raul's speech the US president had slightly loosened the 47-year-old embargo, which Havana calls a blockade. Obama also called on Cuba to free political prisoners and cut taxes on remittances to the island.
In an article published on Wednesday Fidel, 82, said that Obama "without a doubt misinterpreted Raul's declarations". Raul's words were not an invitation to dialogue without preconditions, Fidel wrote.
"When the president of Cuba said he was ready to discuss any topic with the US president, he meant he was not afraid of addressing any issue. That shows his courage and confidence in the principles of the Revolution."
Some analysts concluded Fidel was slapping down his 77-year-old sibling but it seemed just as likely that Raul's words had in fact been misconstrued. His line about "everything" being up for discussion was made, apparently unscripted, during a heated speech which denounced US policy. Cuban officials did not depict the speech as breaking new ground.
Relations between Havana and Washington have been frozen since 1962 when John Kennedy placed draconian trade and economic restrictions on the communist island. Previous hopes of detente, notably during the Carter administration, ended up stillborn.