The chairman of the House Intelligence oversight sucommittee charged yesterday that the Central Intelligence Agency has "buffaloed" Congress into accepting a warped interpretation of the law governing covert operations.

Subcommittee Chairman Les Aspin (D-Wis.) said the Hughes-Ryan amendment of 1974 was intended to require notice to the congressional committees before the CIA could undertake covert activities in foreign countries.

The CIA has maintained that it need not give Congress prior notice President Carter opposes provisions of a proposed charter for the CIA that would require prior notice even more explicitly. White House aides and CIA officials contend that this would encroach on the president's constitutional prerogatives.

However, Aspin, said a study by a senior lawyer for the Library of Congress' Congressional Research Service concluded that prior notice is required by the 1974 law.

"But in an effort to cooperate with the intelligence community, we have accepted a warped interpretation of the law" Aspin said.

"The key term is 'unless and until,'" he declared. "The CIA cannot launch a covert action 'unless and until' Congress has been notified. And that plainly means prior notification."

The Hughes-Ryan amendment was enacted after a furore over CIA activities in Chile. Under it, the CIA may not undertake any foreign operation -- other than those strictly limited to intelligence gathering -- "unless and until the president finds that each such operation is important to the national security of the United States and reports, in a timely fashion, a description and scope of such operation to the appropriate committees of Congress. . . ."

The CIA has always emphasized the "in timely fashion" clause. The words, "and until," were added on the House floor at the behest of Rep. John Burton (D-Calif.) shortly before the law was passed in final form.

In practice, the CIA notifies key members of the House and Senate Intelligence committees, and several other panels, in advance. But CIA officials contend that the practice ought not to be nailed down in law on the grounds that there always will be a need for unforeseen exceptions.

The practice, in any case, is somewhat diluted. The notifications sometimes are extremely vague. Both Presidents Ford and Carter have made so-called "generic findings" declaring in advance that the CIA could carry out a wide range of covert operations dealing with narcotics, terrorism and counterintelligence, according to informed sources.

Other secret subjects, sources say, since have been added to the list. The congressional committees are not told of the specific covert actions dealing with those problems unless they ask about them.

The author of the Library of Congress legal study, Raymond J. Celada, said the legislative history of the Hughes-Ryan amendment strongly suggests that the conditions it laid down -- for presidential approval and for notice to Congress -- "must be complied with before the planned covert activity is put into operation."

The study pointed out that the law was enacted after a more stringent effort to outlaw covert activities. The House version, drafted by the late Rep. Leo Ryan (D-Calif.), was the one that became law, with Burton's amendment. Celada concluded that it still was meant to require prior notice, except in wartime when reports "in timely fashion" would suffice.

His study was done in 1975 and made public yesterday by Aspin, who recently discovered it.

The CIA has been seeking repeal of the Hughes-Ryan amendment for years, primarily on the grounds that it requires reports to too many congressional committees. But Aspin said only three -- the two Intelligence committees and a House Appropriations subcommittee -- systemically review covert actions.