Now, on the 30th anniversary of the coup, professors, journalists and citizen activists around the world are continuing to expose the full role of the US government in financing and promoting this bloody coup, which ushered in the 17-year military dictatorship headed by General Augusto Pinochet.

Thousands of top secret documents which were declassified over the past five years have now been synthesized in a new book, The Pinochet File, by investigative reporter Peter Kornbluh of the National Security Archives, a Washington-based investigative centre. "The US created a climate of a coup in Chile, a situation of chaos and agitation," said Kornbluh. "The CIA and state department were worried that the [Chilean] military ... were not ready for a coup."

The top secret documents accumulatively detail the crude workings of Washington during the Cold War. "It is firm and continuing policy that Allende be overthrown by a coup," reads a CIA document from October 1970. "It is imperative that these actions be implemented clandestinely and securely so that the USG [US government] and American hand be well hidden."

Two days after this document was written, top CIA officials proposed a terrorist campaign to stun the Chilean people into accepting a military regime.

"Concur giving tear gas cannisters and gas masks ... working on obtaining machine guns," reads a CIA memo dated October 18 1970.

"Use good officers ... Some low-level overflights of Santiago and bomb drops in areas not likely to cause casualties could have great psychological effect and might swing balance as they have so many times in past in similar circumstances."

While conservative Chileans argue that the coup was a home-grown affair, the current Chilean minister of education, Sergio Bitar, says: "That internal crisis was activated by the North American policies against it. We see how they energetically obstructed all types of credit from the World Bank and the InterAmerican Bank ... these were decisive actions. This were political and financial pressures that were very relevant [to the ensuing coup.]"

The US effort to destabilise Chile was led by a policy of massively funding and bribing non-leftwing Chilean politicians.

Throughout the 1960s, the US secretly spent millions funding political parties of their choosing - usually the moderate Christian Democrats led by Eduardo Frei Montalva. By the early 1970s, Chilean society had become so leftwing that Washington decided to change tactics. First, President Nixon authorised $10m to be spent "to make the economy scream".

He also authorised pro-coup initiatives designed to destroy the traditional reluctance of Chilean military men to take over civilian government.

"Pinochet will not be a stumbling block to coup plans", reads one memo written six months before the coup, in which the American government looks to build a veritable Dream Team of coup plotters. "The navy and air force are ready ... the military is getting ready to move."

As part of a particularly crude effort to remove army officers who supported democratic rule, the CIA organised to kidnap Rene Schneider, a Chilean army general.

That plot was botched; Schneider died, and today his family is suing the US government and Henry Kissinger in particular for playing a role in his murder.

Citing documents declassified in the past few years, the lawsuit alleges that the US government paid $35,000 to the men who plotted the actions against Schneider.

"I don't want revenge, I want the truth to be established," said a son of the murdered general, also named Rene, who now lives in Santiago and works for a television station.

Immediately after the coup, US officials worked hard to ease international criticism of the human rights record of the Pinochet regime. Rather than fear Washington¿s reproach, the military regime repeatedly sought help and advice.

Just weeks after the coup, the US ambassador in Chile sent a memo to Henry Kissinger noting that "the military government of Chile requires adviser assistance of a person qualified in establishing a detention centre for the detainees ... adviser must have knowledge in the establishment and operation of a detention centre".

Even when the full extent of the torture and executions in Chile were well known, the US government sought to integrate the Pinochet regime into international business circles.

Probably no figure more personalised the cruelty of the Pinochet regime than the head of its secret DINA police force, Manuel Contreras.

Previously classified documents now confirm that, not only was Contreras on the CIA payroll, but that when he came to Washington during the height of human rights abuses, the US state department had specific tasks for him.

"Contreras was also asked to check in with Anaconda [Copper] and General Motors to encourage them to resume operations in Chile."

· A documentary, The Other 9/11, is broadcast at 11pm on Thursday September 11 on BBC Four