Athens (AFP) - Former Cuban president Fidel Castro on Monday congratulated Greek Prime Minister Alexis Tsipras for his "brilliant political victory" in the country's referendum, which saw voters deliver a resounding 'No' to more austerity.

Castro wrote to Tsipras saying he had "closely followed this victory" on Venezuelan TV station Tele Sur, according to a statement from the Tsipras office.

The letter from the 88-year-old, released to the media, described Greece as a country well-known to Cubans for its history and famed contributions to "the most complex of all human activities, art and political science".

Castro wrote that Greece has "the admiration of the Latin American and Carribean peoples" for the way in which it "defends its identity and its culture against external aggression".

He signed off by wishing "the greatest success" to his "esteemed colleague" Tsipras.

Several South American leaders on Monday hailed the Greek referendum result, including current Cuban President Raul Castro -- Fidel Castro's brother -- and his Argentine and Bolivian counterparts Cristina Kirchner and Evo Morales.