HAVANA - The 68-year-old son of Cuba's former leader Fidel Castro has killed himself in Havana, according to Cuban state media.

Fidel Ángel Castro Díaz-Balart was found on Thursday morning and is said to have suffered from depression.

The first-born son of the late president was nicknamed "Fidelito", or Little Fidel, after his father. He was a nuclear physicist, trained by the former Soviet Union.

"Fidel Castro Díaz-Balart, who had been treated by a group of doctors for several months due to deep depression, took his life this morning," Cuba's official newspaper Granma reported - little more than a year after his father. State television said he had been receiving medical treatment as an outpatient in recent months, following a hospital stay. Fidel Ángel Castro Díaz-Balart had taken his own life after suffering with deep depression which doctors had been treating him for over several months, state TV said.

As much as the death itself may shock ordinary Cubans, it was those unexpected circumstances which caught them by surprise.

As the personal lives of members of the Castro family are generally kept away from the public eye, almost no-one will have known he suffered mental health issues prior to the announcement of his death.