The Pentagon is considering widening the use of lie detectors because "there is a feeling in the building that too much sensitive information of a national security nature is getting into the hands of our enemies," Henry E. Catto Jr., assistant secretary of defense for public affairs, said yesterday.

Catto, when asked for examples after he made that statement at the Pentagon news briefing, declined to give any. But he said reporters are "primary beneficiaries" of loose security which provides information for stories.

"Polygraphs can help pinpoint a quaint custom around here of arrogating to oneself what shall be classified and what shall not be," he said. "We want to discourage people with hidden agendas" from working outside "the democratic process."

The Pentagon has drafted a directive that would allow lie detectors to be used on a much wider basis than they are under the current rules embodied in Defense Department directive 5210.48 issued on Oct. 6, 1975.

The new directive, as now written, would allow Pentagon polygraph teams to administer lie detector tests in other government departments upon request.

Catto said that the draft directive, if approved by Defense Secretary Caspar W. Weinberger, would be published in the Federal Register. The draft is currently under review by William H. Taft IV, Pentagon general counsel. Catto said he does not know if and when the final draft will be issued. But he said any new regulation would preserve the existing right to refuse to take a lie detector test.

Asked how this intent squared with the Pentagon's current effort to get people in especially sensitive jobs to waive their right to refuse polygraph examinations, Catto said he was not aware of that situation but would check.

Catto, late in the briefing that was dominated by questions and his answers about the polygraph directive, said he had not read it. He said at another point that he did not know whether Weinberger as a lawyer considered polygraph examinations a reliable form of evidence.

The Pentagon's move to widen the use of polygraphs comes at a time when the tests are under deep suspicion in the courts. John Shattuck, executive director of the American Civil Liberties Union, said that polygraph tests are so unreliable that federal judges will not admit them as evidence even when accused persons press for their admission.

Asked if the Pentagon was trying to intimidate its employes by moving toward wider use of polygraphs, Catto said the department is trying to make people "aware that there is a national security problem and acts might have consequences."

The General Accounting Office recently reported that the Pentagon had launched 68 investigations from January, 1975, through March, 1982, using polygraphs in only two.

One of those two cases was the Pentagon's unsuccessful attempt to find the sources for The Washington Post story of Jan. 8 disclosing that an internal Defense Department study concluded that it would cost $750 billion more than publicly estimated to carry out President Reagan's five-year rearmament program.

Deputy Defense Secretary Frank C. Carlucci, formerly deputy director of the Central Intelligence Agency, is a strong believer in giving lie detector tests and ordered them used during the January investigation.

The ACLU has contended that polygraph examinations are not only unreliable but, when given in the coercive atmosphere of a government investigation, violate constitutional rights by invading privacy and forcing people to incriminate themselves.