Rumours are growing about the health of former Cuban leader Fidel Castro after a Venezuelan doctor claimed the 86-year-old had suffered a massive stroke.
There was no official comment by the Cuban government but state media published a letter said to be from Mr Castro and relatives at home and in the United States have denied that he is at death's door.
Social media sites and some news organisations have reported the claims that Mr Castro is in a vegetative state, with only weeks to live.
The same doctor, Jose Rafael Marquina, has made some claims before that have not been verified. He told Spain's ABC newspaper that Mr Castro had suffered a "massive embolism of the right cerebral artery" and while not on life support or breathing artificially, was "moribund" at a house in a gated former country club in western Havana.
He also said that Venezuelan President Hugo Chavez had travelled suddenly to Havana to be with his friend and ally, an account that could not be immediately verified.
Dr Marquina told the Associated Press his sources were in Venezuela, but he would not identify them. He also indicated he had received corroborating evidence from sources on Twitter, but would not say who.
In April, Dr Marquina said that Mr Chavez, who has been battling an undisclosed kind of cancer, was in his "last days" and would not last to November. With less than two weeks to go, the Venezuelan leader says he has beaten the illness and appears stronger in public.
Mr Castro's health is considered a matter of national security in Cuba and few details are released. Rumours that the former Cuban leader has died or is near death have circulated repeatedly for years, but they gained force after he failed to issue a public statement congratulating Mr Chavez on his October 7 election victory.
Mr Castro has not been seen in public since March, when he received visiting Pope Benedict XVI. He has also stopped writing his once-constant opinion pieces, the last of which appeared in June. In the letter attributed to Mr Castro he congratulated graduates of a medical school on the occasion of its 50th anniversary.
Two close family members have also recently denied he is in grave condition. Juanita Castro, his sister, said in Miami that reports of her brother's condition are "pure rumours" and "absurd". Son Alex Castro told a reporter for a weekly Cuban newspaper that his father "is well, going about his daily life."