BRASILIA (Reuters):

Argentina's armed forces notified the military dictatorships of Brazil and Chile before staging the 1976 coup that toppled the government of Isabel Peron, according to recently declassified documents.

The communication was an early sign of the cooperation that would eventually become Operation Condor, in which the region's right-wing military governments worked together to hunt down and execute dissidents in hiding.

Peron was sworn in as president in 1974 after her husband, then-President Juan Domingo Peron, died in office. Peron's third wife, she had been serving as his vice-president.

Lorenzo de Montmollin, the head of Argentine naval intelligence, notified Brazilian and Chilean officials of the military's plans weeks before deposing Peron, according to documents obtained by Reuters from Brazil's foreign ministry, which have been declassified but not made public.

The coup took place on March 24, 1976, ushering in a seven-year military dictatorship that kidnapped and killed as many as 30,000 dissidents.

"Montmollin, declaring that he was specifically authorised by the commander in chief of the Armed Forces to do so, outlined the main steps to be taken by the future regime," Joao Baptista Pinheiro, Brazil's ambassador to Argentina at the time, wrote in a secret telegram dated March 12, 1976.

Pinheiro also transcribed a conversation between a senior Brazilian diplomat and Montmollin in which the Argentine official said Chilean dictator Augusto Pinochet had been notified that a coup was being planned.

The Argentine armed forces asked that Chile abstain from recognising the military government for a while, a request the Chilean authorities agreed to honour, Pinheiro wrote.

Montmollin justified the request by indicating that under the Argentine military regime "subversion would be wiped out, but without ostensive violent repression so as to avoid suffering an international campaign like the one that has been unleashed against Chile."