Cuban vice-president Carlos Lage this weekend sought to dispel growing speculation about Fidel Castro's health, insisting he does not have stomach cancer and is gaining strength after surgery.

"He's been made well by the operation and is recuperating favourably," said Mr Lage during a visit to Bolivia for the opening of a constitutional assembly.

Mr Lage's comments were the most detailed by a Cuban government official about their leader's medical condition since last Monday, when Castro announced he had undergone surgery for intestinal bleeding and temporarily handed over power to his brother, Raul. The leader turns 80 on August 13.

Havana has provided no details and released no pictures of Castro - fuelling speculation around the world about his condition.

Raul Castro, the defence minister, also has not been seen in public since the announcement.

Authorities have been calling on Cubans to reaffirm their commitment to Castro and the government, and have beefed up security.