The State Department yesterday expressed "deepest concern" for the fate of Nobel Laureate Andrei Sakharov and deplored his detention by authorities in Moscow.

"All those who value freedom will deplore this official act of repression against a man who has struggled valiantly for human rights in the Soviet Union," it said.

The exile and prospect of a trial for the prominent Soviet scientist is sure to strain already tense U.S.-Soviet dissident and was encouraged at one time by President Carter to continue his campaign for human rights in the Soviet Union.

"Words cannot add to the moral grandeur of Dr. Sakharov's enormous and continuing contribution to the cause of human rights in the U.S.S.R. and around the world," the U.S. statement said. His fate is a "cause of deepest concern for all free societies where his courageous struggle ... is celebrated," it added.

The U.S. statement echoed those of government leades, prominent human rights organizations and even Communist parties throughout the Western world.

In London, British Foreign Office Minister Richard Luce summoned Soviet Ambassador Nikolai Lunkov and expressed the British government's anxiety and distress that Sakharov and his wife had been detained.

During a 30-minute meeting, Luce told the Soviet envoy that Britain would deeply deplore any action concerning Sakharov that was not in accord with the 1975 Helsinki declaration and its provision about freedom of thought and political rights.

Western diplomatic sources said in London that the Sakharov detention, coming on the heels of the invasion of Afghanistan, would reinforce the views of those who want Western countries to boycott the Moscow Olympic Games.

At The Hague, a Foreign Ministry spokesman said the Dutch government was deply shocked at the news from Moscow.

"If the reports from Moscow are true, then this constitutes a flagrant violation of the letter and spirit of the Final Act of Helsinki embodying the principle of respect for human rights," he said.

Dutch Socialist leader Ed van Thijn, who heads the committee for the country's Olympic Games and human rights, denounced the Soviet moves as a "gross violation" of the Helsinki acords in an interview with Agence France-Presse.

"Your committee was not in favor of a boycott of the Olympic games in Moscow because we are of the opinion, as was Mr. Sakharov, that one must use all contact with the Soviet Union to defend human rights," he said. "But this Soviet response forces us to reconsider with the committee of other countries our participation in the games."

A West German official said the first impression in Bonn was that "the Soviets are trying to clean up their streets before the Olympics."

Sharp criticism also came from the Communist world, however. Leading Yugoslav dissident Milovan Djilas said the "action against Dr. Sakharov is a sign that the darkest forces in the Soviet Union are gaining the upper hand ... everything that is reasonable and decent in the Soviet Union will be gone if he is exiled.

Italy's Communist Party daily newspaper L'unita, in a scathing editorial on the Sakharov detention, said the Soviet Union was incapable of resolving tensions tolerantly and Sakharov's treatment was an example of "a monolithic vision of a society that considers anything different as pathological."

The French Communist Party had no immediate comment.

The sentiment among human rights groups was also sharply critical of the Soviets. Amnesty International, the London-based Nobel prize-winning group, sent a leter to the Soviet Embassy in London expressing shock at Moscow's action. They were joined in protests by such groups as the International League for Human Rights and the U.S. Helsinki Watch Committee.

The White House said the official U.S. comment was issued by the State Department, but there were indications that further comments would be coming from Carter administration officals in the future.

There was little comment from Capitol Hill, but Sen. Henry M. Jackson (D-Wash.), a staunch human rights advocate, said "Andrei Sakharov is one of this century's most courageous champions of individual freedom, decency and the huamn values. The Kremlin's attempts to dishonor and incarcerate Sakharov will outrage freedom-loving peoples throughout the world."

The detention also drew the wrath of the Soviet Union's most prominent exiles. National Symphony Orchestra conductor Mstislav Rostropovich, who was stripped of his Soviet citizenship by Moscow authorities, issued a statement saying, "The Soviet government thinks that above the clanking music of tanks grinding through Afghanistan, the world will not hear the groans of the strangling, honest people of my country ... Sakharov ... has become the personal symbol of the human striving for freedom for all humanity."

The American scientific community, which has a special affinity for Sakharov, was shocked by the news.

"Along with the rest of the scientific community, the Committee of Concerned Scientists is profoundly shaken by today's events," said biologist Max Gottesman, cochairman of the 5,000-member group based in New York. "The expulsion of academician Sakharov from Moscow and the actions of the Soviet government in stripping him of his honors are repulsive."

"Coming as they do in the aftermath of the Soviet incursion into Afghanistan, we are concerned that (the Soviet actions) portend a change which threatens the continuance of cultural and scientific relations between our two countries."

Jeremy Stone, a spokesman for the Federation of American Scientists, an organization of about 5,000 U.S. scientists, was espcially critical of the Soviets.

"The Soviet leadership is battening down the hatches against any internal dissent by making an example of the most senior internal dissenter, Andrei Sakharov," he said. "By silencing him with internal exile, they are incurring great costs in the animosity they will produce among American scientists."