One of Fidel Castro's sons has said his father is in good shape despite a long public silence that has fuelled speculation about the 86-year-old former Cuban president's health.

Alex Castro was quoted by a state-run newspaper as saying "the comandante" was going about daily life as normal, reading and exercising. Rumours of the former leader's purportedly declining health surfaced anew last week after he failed to publicly congratulate Venezuelan president Hugo Chavez on his re-election. He has not been seen in public since late March.