The Reagan administration's reinterpretation of the 1972 Antiballistic Missile (ABM) Treaty to allow development of exotic missile defenses is "the most flagrant abuse of the Constitution's treaty power in 200 years," according to a report released yesterday by the Senate Foreign Relations Committee.

The committee said the reinterpretation -- different from the one presented to the Senate during its ratification in 1972 and adopted by the Nixon, Ford and Carter administrations -- constituted "not merely an attack on one treaty but a

cavalier disregard for the rule of

law itself, domestic and international."

It was the second setback in a week to the administration's position that it can reinterpret the treaty in a way that permits it to perform tests for its space-based antimissile defense program that a traditional interpretation of the treaty would prohibit.

Last Thursday, the Senate voted to deny funds for testing and development of exotic missile defenses under the "broad" or permissive treaty interpretation announced by the administration in 1985.

The 106-page Foreign Relations Committee report supported the argument of Sen. Sam Nunn (D-Ga.) that the reinterpretation will make impossible prompt ratification of a proposed U.S.-Soviet treaty eliminating medium-range and shorter-range missiles.

"This report underscores the profound constitutional issues which will surround Senate consideration of an agreement" on the intermediate-range missiles if the administration continues to back the reinterpretation, said Sen. Joseph R. Biden Jr. (D-Del.), chairman of the European affairs subcommittee and a candidate for the Democratic presidential nomination.

Nunn, chairman of the Senate Armed Services Committee and a prominent critic of the administration's permissive reading of the ABM treaty, has previously argued that the reinterpretation of the ABM treaty will force the Senate

to scrutinize the entire, secret re- cord of negotiations for the new missile pact, known as the intermediate-range nuclear forces (INF) treaty.

The committee argued that this painstaking process will be required to assess whether negotiators for the two superpowers have made private remarks that contradict the language of the intermediate-range missile treaty or the public assertions of Reagan administration officials.

The report said such a review is necessary because the administration bases its case for reinterpretation of the ABM treaty on ambiguous, private remarks of U.S. and Soviet negotiators that are contradicted by public testimony of some U.S. officials during Senate ratification hearings at the time, and by subsequent, official U.S. government statements.

"Thus, the administration's theory of treaty-making . . . could severely complicate and greatly prolong the committee's consideration of {an intermediate-range} missile treaty," the committee report said.

U.S. officials, who nailed down additional details of the treaty during talks here with Soviet Foreign Minister Eduard Shevardnadze last week, have said they are optimistic that it could be signed and ratified by next summer or fall, before Reagan leaves office.

The administration has already said it is willing to make the record of the intermediate-range missile treaty available to the Senate, and Shevardnadze said last week that his country did not object.

But the committee's report -- based on a series of hearings last spring with administration officials, legal experts, and former U.S. negotiators -- said routine disclosures of secret negotiating records "would clearly have a . . . chilling effect on future negotiations, inhibiting candid exchange and inviting posturing on the part of the negotiators for both domestic and international audiences."

In addition to threatening a delay in the ratification of the treaty, the report, which was approved by the Foreign Relations Committee's Democratic majority, supported Senate Resolution 167, a nonbinding demand that the administration reaffirm the traditional, "narrow" ABM treaty interpretation.

In particular, the report cited a private memorandum from Assistant Attorney General Charles J. Cooper to State Department legal adviser Abraham D. Sofaer. The report said the memorandum reportedly "came to conclusions generally supportive" of the committee's position.

Cooper told Sofaer that if the Senate relied on unequivocal remarks by administration officials in approving the ABM treaty, "we believe the president would, in effect, be estopped from taking a contrary position in his subsequent interpretation."

The committee report said recent reports by Sofaer favoring the broad interpretation contained "critical omissions and numerous misrepresentations" and constituted a "deliberate attempt to rewrite history."

"Such haste and bias can only be explained by an ideological motivation on the part of certain administration officials to circumvent . . . analysis of their solemn U.S. treaty obligations and to subordinate such obligations to their own policy preferences," the committee report said.

The report cited approvingly, however, a statement by Sofaer in a report released earlier this month in which he said that the United States had consistently supported the narrow treaty interpretation in bilateral discussions with the Soviet Union after the treaty was signed.

Sofaer's report revealed that the three military services, the Joint Chiefs of Staff and some other Defense Department officials objected to the narrow treaty interpretation as early as 1973, in an attempt "to keep open the options for future U.S. research and development efforts that would have been precluded" by the narrow interpretation.

But Sofaer's report also stated that their views were not reflected in statements made on behalf of the entire U.S. government until 1985, when the Pentagon finally had the "technological capacity" to take advantage of a more permissive interpretation.

The State Department declined to comment on the committee's report yesterday and Sofaer could not be reached. But Sen. Jesse Helms (R-N.C.), the committee's senior Republican, expressed support for the Reagan administration's position in an appendix to the


Helms said the Senate "is not empowered in law to interpret treaties" and that such interpretation was the responsibility of the executive branch.

The Soviets proposed last week that the administration abide by the traditional interpretation of the 1972 treaty for at least another 10 years as an inducement to reaching an agreement on reducing strategic, or long-range, nuclear missiles. The Soviets said they adhere to the traditional interpretation of the treaty.