By JUAN O. TAMAYO

  The CIA correctly predicted five years ago that Colombia's rightist paramilitary militias would grow into a major challenge for both Bogotá and Washington
  unless the Colombian military managed to halt leftist guerrilla advances, according to recently declassified reports.

  From 4,000 fighters in 1997, the illegal paramilitaries today have 11,000 men, accused of more than 1,000 execution-style killings last year and increasing
  involvement in Colombian politics and the narcotics trade.

  ''The growth of paramilitary violence is likely to complicate U.S. interests . . . in the areas of human rights and counter-narcotics,'' said a June 1997 report
  by the CIA's Office of Asian Pacific and Latin American Analysis.

  The report was one of 70 recently declassified CIA, State and Defense Department documents on U.S. counter-narcotics efforts made available last week
  by the National Security Archive, an independent Washington organization.

  Most of the reports, dating to 1988, show constant tensions between U.S. attempts to limit aid to Colombia and Peru to fighting drugs, and those
  countries' determination to use the aid to fight leftist guerrilla foes.

  ''A lot of what they [the documents] show is the expansion of the counter-narcotics box to include counter-insurgency,'' said Adam Isacson, a Colombia
  expert at the Washington-based Center for International Policy.

  President Bush has asked Congress to lift some of the restrictions on U.S. counter-narcotics aid to Colombia, such as helicopters, to allow the Colombian
  armed forces to use it against leftist guerrilla foes.

  The CIA report on the paramilitaries said they ''will continue to expand in membership, capability and influence'' barring ``a significant improvement in
  Bogotá's capability to impose security in the Colombian countryside -- which we believe is unlikely.''