Cuban Leader Fidel Castro has said he is recovering and feeling stronger in his first live radio broadcast since emergency stomach surgery forced him to relinquish power in July.

Sounding much healthier and more lucid than he has in taped video clips released during his convalescence, Mr Castro laughed frequently in a half an hour chat with Venezuelan President Hugo Chavez that was marked by boyish humour.

"I am gaining ground," he said on his top ally's nightly radio show, which was later played on Cuban state television.

"I feel I have more energy, more strength, more time to study."

His guest appearance came as a surprise to listeners.

Mr Chavez said his Energy Minister was on the line, but the 80-year-old Cuban's voice broke in.

"Listen, my distinguished and dear friend, how are you?" he said.

The two icons of Latin America's left, who pride themselves on their anti-Americanism, exchanged pleasantries in English.

Mr Castro later commented on the fall of world stock markets on Tuesday, the worst in years, and said it was proof of his view that capitalism was in crisis.

Mr Chavez calls Mr Castro his mentor and has frequently visited him during his convalescence, with images of the meetings broadcast afterward.

A video clip of their last meeting released almost a month ago showed Mr Castro had put on weight but remained frail.

Mr Castro has not been seen in public since the surgery.

In power since 1959, Mr Castro handed over control temporarily to his brother, Defence Minister Raul Castro, on July 31.

Mr Castro's condition is a tightly guarded state secret, and his illness was officially attributed to the 'extreme stress' of his workload.

Cuba watchers say Mr Castro's backstage presence and the carefully staged meetings with Mr Chavez could be reassuring to Cubans and help his successors maintain the one party state.

- Reuters