Cuban President Raul Castro (Left) casts his vote at a polling station in Santiago de Cuba Province during an election to ratify a new National Assembly on March 11, 2018, a key step toward the election of the first Cuban president outside the Castro family in 60 years. Photo: VCG

The CIA made its first known attempt to assassinate a leader of the Cuban revolution in 1960, offering $10,000 to a pilot flying Raul Castro from Prague to Havana to arrange an "accident," according to newly published declassified documents.

Pilot Jose Raul Martinez, who had been recruited by the CIA, asked for - and received - assurance from the agency that it would provide ­university educations to his two sons if he died during the operation, ­according to the documents published by the Washington-based National Security Archive research institute.

After Martinez left for Prague, CIA headquarters in the United States told its Havana station to cancel the mission. 

"Do not pursue," the cable said. "Would like to drop matter."

At that point, the pilot was already out of contact. When he returned to Cuba, Martinez told his handler that "he had no opportunity to arrange an accident such as we had discussed."

The plot came to light as Castro, the 89-year-old brother of late ­revolutionary leader Fidel Castro, prepares to leave Cuban politics by stepping down as head of the Community ­Party of Cuba. 

"These documents remind us of a dark and sinister past in US operations against the Cuban revolution," said National Security Archive analyst Peter Kornbluh.

Fidel Castro defied 11 American presidents and survived numerous assassination plots - 638 according to Guinness World Records - as well as a failed 1961 attempt by 1,400 anti-Castro Cubans, who were trained and financed by the CIA, to land at the Bay of Pigs in an attempt to overthrow the Cuban government.