Argentina has decided to make public all secret archives of the armed forces to help uncover human rights violations committed under military rule.
Some 30,000 people may have been killed during the "dirty war"
The decision was announced by Defence Minister Nilda Garre.
It comes on the eve of the 30th anniversary of the coup, by which the military seized power in 1976.
Human rights groups say up to 30,000 political opponents of the regime were kidnapped, detained and later executed during seven years of military rule.
The government issued a decree to guarantee unrestricted access to information on what it said were grave acts committed during the so-called Dirty War.
It ordered all the branches of the armed forces and the Ministry of Defence to provide access their secret files when required.
Recovered documents will be kept at the National Memory Archive, an institution created by President Nestor Kirchner three years ago.
Correspondents say the secret files could play a key role in trials against former military officers accused of human rights abuses, after the Argentine Congress voted to scrap laws protecting them from prosecution in 2003.
Some high-ranking officers such as Gen Rafael Videla - who seized power in 1976 - are under house arrest over the illegal adoption of children born to political prisoners during military rule.
On Friday, President Kirchner is expected to lead an official ceremony to mark the anniversary of the coup.
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