The first public statement in almost four months from Fidel Castro appeared in Cuba's state media on Wednesday, as rumors persist about the 86-year-old revolutionary icon's health.

Castro has not been seen in public since March 28, when Pope Benedict XVI paid a landmark visit, and briefly the following week on April 5 with Chilean student leader Camila Vallejo -- both appearances more than six months ago.

Health Minister Roberto Morales read out a message from Castro on Wednesday at Havana's Institute of Medical Sciences, praising graduates for "honorable missions in far-off corners of the world in very difficult circumstances."

The statement was released five days after Alex Castro, one of the ex-president's sons, said his father is "going about his daily activities," and "exercises, reads and stays in shape."

Following his 1959 revolution, which closed a long era of Washington dominance over Cuba., Castro held onto power despite the efforts of US administrations over the decades to pressure his Communist regime.

Castro ceded the presidency to his younger brother Raul, 81, in July 2006 for health reasons.

Prior to Wednesday, nothing had been published in Castro's name since June 19.