The revelations appeared Wednesday on the web site of the National Security Archive, a Washington-based independent research organization.

The group posted more than two dozen declassified documents detailing the CIA´s recruitment of senior Mexican officials over the 1956-1969 period.

The highest-placed CIA sources were Gustavo Díaz Ordaz, who served as president of Mexico from 1964-1970, and his eventual successor, Luis Echeverría, who was interior secretary.

"Never before had there been official verification, via declassified documents, that the CIA relied on high-level Mexican government officials to provide intelligence reports on political events in that country," Kate Doyle, director of the Archive´s Mexico Project, told EFE.

At a time when the Institutional Revolutionary Party (PRI), which governed for more than 70 years, "was using coercion and violently repressing the opposition in that country, the CIA was giving the United States deceptive information obtained from high-level officials in that government," Doyle said.

Doyle said the documents described a situation in which both Díaz Ordaz and Echeverría "gave CIA officers information that they wanted the U.S. government to believe about the Tlatelolco massacre."

This was another example of how the CIA, as with Iraq, did not do a good job of "obtaining intelligence information in an objective manner and analyzing it," Doyle said.

"If the CIA sources (at that time) are the president and intelligence chiefs of a country, the agency is not giving the U.S. government a complete and objective picture of what is happening in that country," Doyle said.

The expert said that, based on the intelligence the CIA provided to the U.S. government at the time, Washington "never questioned the repressive actions of the Mexican government and never questioned the legitimacy" of the PRI.

The documents shed light on what the CIA knew and did not know about the events of Oct. 2, 1968, in Mexico City, where a student protest ended with a massacre in Tlatelolco Plaza.

GOV´T VERSION ACCEPTED

Long-time CIA station chief Winston Scott relied on high-level officials of the Mexican government, among them Díaz Ordaz and Echeverría, to keep Washington informed about the student movement that was challenging the PRI´s monopoly on power, according to the National Security Archive.

"Scott relied on the government´s version of the Tlatelolco killings, reporting as ´intelligence information´ its fictional accounts of the events," the National Security Archive said on its web site.

While Mexican authorities put the number killed in Tlatelolco at 39, hundreds are believed to have been slain in the square by members of a government-run paramilitary squad known as the Falcons, which also played a role in other acts of repression during the PRI´s "Dirty War" against leftists, which went on until about 1980.

The CIA´s code name for the network of spies and informers in Mexico was LITEMPO, and it included at least a dozen people, among them close friends of Scott.

Two men on the list were later tried for war crimes.

The documents do not reveal how much the CIA paid its informers in the LITEMPO network, "but at least two CIA officials thought it was excessive," Jefferson Morley, a writer for washingtonpost.com and author of a forthcoming biography of Scott, said in an accompanying article on the National Security Archive web site.

He said Scott made a "personal gift" of 1,000 rounds of .223 Colt automatic ammunition in 1963 that was ultimately passed on to Díaz Ordaz.

Morley goes on to cite one- time British intelligence operative Ferguson Dempster - an old friend of Scott´s - to the effect the CIA station chief provided a daily report on "enemies of the nation" to President Díaz Ordaz.

´DIRTY WAR´ REPORT

In February, the National Security Archive published on its web site a copy of a draft report on the Mexican "Dirty War" that the country´s current conservative government has yet to publish.

The initial draft accuses the administrations of Presidents Díaz Ordaz, Echeverría and José López Portillo of committing "crimes against humanity that culminated in massacres, forced disappearances, systematic torture and genocide."

Under Mexican law, the term "genocide" can refer to instances of mass murder that fall short of the attempted extermination of an ethnic, racial, religious or other group.

Outgoing President Vicente Fox, whose election victory in 2000 ended the PRI´s 71-year reign in Mexico, appointed a special prosecutor to track down those responsible for "Dirty WarW offenses, but those efforts have been hampered by a lack of support from the government.