The Carter administration met unexpectedly strong criticism yesterday in Senate Foreign Relations Committee hearings on legislation to allow continued relations with Taiwan after diplomatic recognition of the Peking government.

Many senators spoke out - some with uncharacteristic vehemence - on the need to include in the legislation a statement of U.S. support for Taiwan's de facto independence in the future. Senators also were critical of proposed protections in the legislation for Taiwanese assets and future Taiwanese representatives in this country.

"The bill is going to be substantially revised," committee Chairman Frank Church (D.-Idaho) said after a full day of hearings. "Ambiguities in the bill leave far too many questions unanswered," he added.

The administration has accepted the inevitability of some congressional tinkering with the Taiwan legislation, which is needed to provide a legal basis for maintaining the U.S.-Taiwan agreements that were in force on a government-to-government basis until Washington recognized Peking.

The United States now proposes to conduct relations through "institutes," theoretically unofficial entities manned by officials of both countries who will be on leave from their normal job titles, if not from their normal jobs.

With few exceptions, members of the Foreign Relations panel expressed determination to assert congressional support for Taiwan and opposition to any use of force by Peking to reunite it with the mainland.

The ranking Republican, for example, Sen. Jacob K. Javits (N.Y.), sternly asked Deputy Secretary of State Warren Christopher:

"Will the United States government be ready to lay it on the line very clearly... that the United States will not tolerate the use of force... to suffocate Taiwan?" This was absolutely necessary, Javits said.

Javits added, "I'm prepared to forgo it [normalization with Peking], hot as I am for it," if Peking will not accept a strong declaration of U.S. support for Taiwan.

Christopher told the committee the administration saw no need for a new statement on Taiwan, but would work with the committee to find an acceptable one if the committee felt it was necessary.

Church and Sen. John Glenn (D-Ohio) are working on a statement. Glenn said last night he had drafted one in the form of a resolution stating America's "deep and abiding concern for the people of Taiwan," and asserting U.S. determination to maintain good relations with Taiwan, to supply defensive weapons to Taiwan, and to act appropriately in response to any threat against. Taiwan.

Administration officials expressed the belief last night that the Foreign Relations Committee would not change the Taiwan legislation so significantly as to jeopardize agreements already reached between the administration and the Peking authorities. But some officials remain uncertain as to what may happen on the Senate floor, or in the House.

Christopher and Defense Secretary Harold Brown, who also testified yesterday, both argued that Peking would be foolish to risk an attack on Taiwan since this would likely rupture Peking's new relationships with the industrial democracies, jeopardizing the Cinese government's modernization program.

Brown gave detailed testimony advancing the administration's view that Peking is militarily incapable of taking Taiwan by force in the years immediately ahead. He added that the United States would not be precluded from taking military action of its own to protect Taiwan in the event of an attack.

Sen. Joe Biden (D.-Del.) tried to challenge the views of most of his committee colleagues yesterday, asserting that it was illogical to try to normalize relations with Peking, implicitly recognizing its claim to ultimate sovereignty over Taiwan, while still seeking "an ironclad, de facto guarantee" that Peking will not use force to reclaim Taiwan. He urged colleagues to "be straight with the American people" and admit they could not have it both ways.