The US Central Intelligence Agency (CIA) had sought to assassinate former Cuban leader Fidel Castro by giving him a bacteria-contaminated diving suit, new documents released by the US National Security Archive suggest.

According to the documents, the plan to kill Castro was designed to be carried out by widely-known American lawyer, Navy officer and political negotiator James Donovan.

Back in 1962, Cuba had captured over 1100 members of a CIA-backed militia that carried out a botched military invasion of the Latin country at the Bay of Pigs.

Donovan, who had earned the designation of “meta-diplomat” for his negotiation skills, was chosen by then-President John F. Kennedy's administration to work out a prisoner swap deal with Castro.

Castro (L) and Donovan

He conducted the first secret negotiations ever with Castro and went on to become “the first trusted US representative” with whom Castro could sit down and discuss US-Cuba ties, according to a recently published book, Back Channel to Cuba: The Hidden History of Negotiations between Washington and Havana.

Donovan successfully negotiated the deal and even managed to get Castro’s permission for over 5,000 of the prisoners’ family members to leave Cuba.

Closely monitoring Donovan’s access to the Cuban revolutionary leader, the CIA decided to seize the opportunity and assassinate Castro.

White House and CIA records reveal that at one point during negotiations with Castro, several CIA covert operations officials came up with a plan to have him killed by taking advantage from his passion for scuba diving.

According to the plan, Donovan would have been the unwitting purveyor of a diving suit and breathing apparatus, respectively contaminated with Madura foot fungus and tuberculosis bacteria, as a gift for Castro.

However, the plan was pulled after Donovan’s CIA handler told him to secure the wet suit before the agency could tamper with it.

Other famous plots to kill Castro involved an exploding cigar, which was supposed to blow up in his face, and also his love of strawberry milkshakes.

The CIA even tried to kill the Cuban leader by rigging a shell with explosives, which was supposed to function as an underwater booby trap.

US President Barack Obama will pay a landmark visit to Cuba in March to enhance ties with the former Cold War adversary. He will be the first US president stepping foot on the island to pursue a historic thaw in nearly a century. The last sitting US president to visit Cuba was Calvin Coolidge in 1928.