Buenos Aires, Jan 29 (IANS/EFE) Argentina has disclosed the secrets of the 'dirty war' waged against the left by the country's military regime 1976-83.

The secret files of Battalion 601, described as the 'brain' that coordinated killings, kidnappings and other abuses, contains the identities of both military and civilian personnel who played a role in the repression.

The declassification of the documents began with an order from Argentine President Cristina Fernandez Jan 1.

The documents presented before the federal Judge Ariel Lijo for review contain data on 3,952 civilians and 345 army personnel who worked for Battalion 601, said Ramon Torres Molina, director of the National Archive of Memory.

The battalion's civilian operatives included everyone from college professors to people who worked as porters, concierges and maintenance men at apartment buildings.

They were used to collect information and to infiltrate guerrilla groups and human rights organisations, with those assigned to infiltration duties given aliases with initials matching those of their real names.

The civilian agents were classified by grades corresponding to military ranks and the most proficient could aspire to the equivalent of colonel.

Torres, who refused to divulge any names until Judge Lijo finishes reviewing the documents, said the intelligence structure was created in the early 1970s and that it survived until 2000, when Battalion 601 was disbanded and its remaining 500 or so civilian operatives dismissed.

Some former commanders of the unit have died and others have been criminally charged, but many military and civilian veterans of the unit are at large, the archive director said.

The archive continues to thumb through more than 4 million digitised pages and thousands of dossiers in search of information about the crimes of a regime that left more than 30,000 'disappeared'.