The best kept secrets of CIA were revealed Tuesday when the agency released hundreds of pages of documents. Known inside CIA as “family jewels” as a sign of their importance the documents are probing hundreds of questionable and illegal activities.

The CIA released the information based on a request from the National Archives under the Freedom of Information Act after years of resisting demands to publicly disclose the documents.

For example, the documents reveal CIA planned to kill the Cuban leader Fidel Castro and was seeking help from the mafia in order to complete the mission.

"The CIA fully understands that it has an obligation to protect the nation's secrets, but it also has a responsibility to be as open as possible," CIA Director Michael V Hayden said.

"I've often spoken about our social contract with the American people, and the declassification of historical documents is an important part of that effort."

According to the documents, other leaders targeted by the CIA included Congo independence leader Patrice Lumumba and Dominican Republic dictator Rafael Trujillo.

Other secretes revealed by the documents are tight to CIA drug experiments on US citizens and the monitoring of groups and individuals opposed to the war in Vietnam.

Although much of the information disclosed in the documents has already been published through the investigation and later by scholars and former CIA agents, historians believes they will offer more details about CIA covert operations during the Cold War.