Former Maj. Gen. Pyotr Grigorenko, the highest ranking Soviet officer ever to openly criticize suppression of human rights in the Soviet Union, was permanently exiled yesterday by a government decree that stripped him of his citizenship.

The action bars Griogorenko, 70, who recently underwent surgery in the United States, from returning home.

The decree, signed by Soviet President Leonid Brezhnev and published yesterday, came just one day after the conclusion of the Belgrade conference on European security and cooperation. The 35-nation conference was marked by East-West confrontation over human rights in the Soveit bloc and failed to produce a substantive document after six months of discussions.

Before he left here for the United States in December, Grigorenko told reporters that he intended to return in May. He said that he had pledged to Soviet authorities that the would refrain from speaking out when he was in America as a condition of being allowed back into the Soviet Union.

Grigorenko had scrupulously observed his part of the bargain. The Supreme Soviet (parliament) decree, however, accused the former general of having "inflicted damage to Soviet prestige."

Using tactics such as deportation, imprisonment and threats, the Kremlin in the past year has substantially reduced the circle of human rights advocates in Russia despite President Carter's advocacy of human rights.

Soviet officials intent on throttling criticism have frequently revoked the citizenship of those it wanted silenced. The list of those who have been denied reentry to the country reads like a who's who of dissident figures, including: Alexander Solzhenitsyn and his wife, Natalya; the writer Valery Tarsis; scientist Zhores Medvedev; and Stalin's daughter, Svetlana Alliluyeva.

Grigorenko has been an unbending critic of the government since 1960, when as a Red Army major general he began asserting that then premier Nikita S. Khrushchev was returning to the repression of the Stalin era.

The tall, bald former soldier was imprisoned in 1964, released, then incarcerated anew in 1969 over his advocacy of human and civil rights for Crimean Tartars. He subsequently was confined to psychiatric institutes until 1974.

GRigorenko went to the United States for a prostate operation, which his friends here said recently had been a success. He and his wife, Zinaida, were accompanied on their trip by a son, Oleg. Another son, Andrei, lives in Long Island City, N.Y. He emigrated in 1975.

Dissidents here said they recently had received letters from Mrs. Grigorenko asking for the proper shoe sizes of friends so she could bring them back presents.

Grigorenko is a friend of Andrei Sakharov, the Nobel prize winning human rights activist and for many years the general's apartment here was a meeting place for dissidents.

The Supreme Soviet decree said the citizenship was being withdrawn because Griorenko "systematically permitted actions imcompatible with the Soviet Union and inflicted damage to Soviet prestige." This is a standard formulation used to cover such actions.

To Westerners with virtually unlimited rights to speak their minds and travel where they please and still return home, the concept of revoking Soviet Citizenship may sound like a blessing in disguise for a dissident who can usually go nowhere and can only speak his mind in the virtually certain knowledge that dire consequences may follow.

But there exists in ordinary Russians as well as those who have quarreled with the government an attachment to the country that sometimes borders on the mystical. Though the notion of the motherland's unique sanctity is mauled almost daily in the controlled Soviet press, emotions of Rodina have an abiding place in the Russian heart.

For the aged Grigorenko, his involuntary exile may be one more torment.