House critics opened a fusillade yesterday against the Carter administration's Panama Canal treaties, charging that they bow 12 "foreign blackmail," endanger U.S. security and defy "the overwhelming opinion" of Americans.

Chief negotiators Ellsworth Bunker and Sol M. Linowitz countered that the pacts will enhance American security, not weaken it, even beyond the year 2000 when Panama takes control of the 51-mile-long waterway.

It was a meeting on lopsidedly hostile ground for the administration, before the House Merchant Marine and Fisheries Committee headed by Rep. John M. Murphy (D-N.Y.).

Murphy charged that "our negotiators appear to have caved in" to demands of "the dictatorial regime of Gen. Omar Torrijos" in "a Milque-toast fashion." He said "many of our former military leaders are fearful of losing the only water passage between the Atlantic and Pacific Oceans" and "the depth of feeling of the American people on this issue cannot be dismissed."

Linowitz acknowledged that "a very large percentage of the American people are opposed to the treaty" now, because, he said, they "have not had the chance to learn the facts about what is involved."

"The image that it is 'an immediate giveaway' is entirely fallacious." said Linowitz."We are going to be running the canal until the year 2000."

Afterward, he said, under the second part, a neutrality treaty, there will be "a firm foundation" for U.S. rights to protect its access if "the canal's neutrality is threatened or violated."

Rep. Carroll Hubbard Jr. (D-Ky.). another critic, asked if the United States in this treaty specifically will have the right "to intervene" if access is challenged.

"We will not use the word 'intervene' or 'intervention.' I can guarantee," Linowitz said. Those are politically explosive words in Latin America. Bunker and Linowitz, stressing that actual treaty language is still under negotiation, said they could be no more specific in open session except to say that the Joint Chiefs of Staff have agreed that U.S. "security needs" are adequately protected.

Republicans on the House committee who were present yesterday, with the exception of Paul N. McCloskey Jr. (R-Calif.), assailed the canal treaties.

"The President and the Department of State have usurped the power of the Congress," charged Rep. Gene Snyder (R-Ky.), and "fed distortions" to the public. Rep. Robert E. Bauman (R-Md.) said the negotiators were giving "double talk" about defense of the canal.

Rep. Robert K. Dornan (R-Calif.) called the agreement "the worst foreign blackmail that I have seen since North Vietnam tweaked the nose" of then-Secretary of State Henry A. Kissinger.

But support came from Rep. James L. Oberstar (D-Minn.) who called the U.S. negotiations "a brilliant piece of diplomacy," and from McCloskey, who questioned "the propriety" of challenging the negotiators in public session while bargaining with Panama is still under way.

And the Carter administration gained full endorsement for the treaties yesterday from Kissinger to add to the strong backing for the treaties on Tuesday from former President Ford.

Kissinger said that after detailed briefings he is convinced that the new accord "sought by four administrations over a period of 13 years" is an acto of "statesmanship, patriotism and wisdom."

He said that his discussions with Gen. George S. Brown, chairman of the Joint Chiefs of Staff, with Bunker and others, assure him that "the new treaty marks an improvement over the present situation" for "secure access" to the Panama Canal.

Kissinger said that the new agreement will have "the support of the countries of the Western Hemisphere," which will reinforce uninterrupted operation of the canal.

A former chairman of the Joint Chiefs of Staff, however, retired Adm. Thomas E. Moorer, took the opposite view before the House committee yesterday, after Bunker and Linowitz testified.

Moorer, and three former chiefs of naval operations, retired Adms. Robert B. Carney, Arleigh Burke and George W. Anderson, wrote to President Carter in June to warn against yielding the canal to Panama.

Moorer reiterated yesterday, "I have yet to see any solid justification advanced as to why the United States should willingly sacrifice the strategic advantages afford to us by our possession of the Panama Canal."

In their earlier, publicized letter, the admirals warned that "the present Panamanian government has close ties with the present Cuban government which in turn is closely tied to the Soviet Union." Moorer reiterated that warning yesterday, that "the Canal Zone could become the satellite base of an adversary . . ."

That theme was threaded through the criticism of the negotiations by Chairman Murphy and other members, with repeated references to Panamanian chief of state Torrijos as "a dictator."

"Your are not being helpful" protested Linowitz at one point, at a time when negotiations are still under way. Panama "is a dictatorship," countered Rep. Snyder, and "if that is not helpful, I am sorry."

The 83-year-old Bunker, maintaining his usual impassivity throughout the hearing, drew a distinction between an "authoritarian regime" and "a dictatorship." Panama, he said, has an "authoritarian government," but, he said, it is "not an outright dictatorship."

Bunker and Linowitz said Panama has abided by its treaty obligations. Murphy strongly disputed that, citing a record of incidents inside the 10-mile-wide Panama Canal Zone, an area that would be reduced by about 65 per cent under the new treaty.

The second dominant issue in the hearing was continuing insistence by the House members that the Carter administration cannot dispose of U.S. property in the Canal Zone by a treaty, "without the consent" of the House as well.

State Department legal adviser Herbert J. Hansell repeated the administration's contention that American property in the zone can be transferred either way, by treaty or by act of Congress. Hansell said Attorney General Griffin B. Bell concurs.

However, Hansell said, the Carter administration has not yet determined which route it will take, and there will be "extensive consultations" with Congress on that.

Robert Beckel, deputy assistant secretary of state for congressional affairs, said "we are beginning our consultations anew" on this sensitive congressional issue, and this will include discussions with House Speaker Thomas P. (Tip) O'Neill Jr.

This indicates that the administration may decide to try to placate its House critics by a compromise. The administration needs legislation in the House, in any event, to carry out many of the terms of the new Panama Canal arrangements, as well as a two-thirds vote in the Senate for both canal treaties.

By bowing to some of the demands in the House on the property transfer issue, the administration may be able to ease its difficult task of getting all the legislation through Congress.

Sen. Strom Thurmond (R.S.C.), a leading Senate opponent of the treaties, predicted yesterday that they will not be ratified "unless tremendous pressure is brought by the administration."

Thurmond announced that he and Sens. Jesse Helms (R.N.C.) and Orrin G. Hatch (R-Utah) plan to visit the Panama Canal Zone today to examine the situation in light of the Aug. 10 agreement-in-principle reached by American and Panamanian negotiators on the two new treaties.

In 1975 Thurmond gathered the support of 38 other senators in opposition to yielding any American control of the Panama Canal. If all 100 members of the Senate vote, it takes 67 votes to ratify a treaty.