The wife of Soviet human rights activist Andrei Sakharov made an emotional appeal to the West today to help him gain admission to a heart clinic in Moscow, saying the conditions of his exile would lead to his death.

A pale and distraught Yelena Bonner, talking to western reporters on a busy Moscow street after police prevented them from entering her apartment, voiced fears that the nuclear physicist "will either die or they will kill him" in Gorki, an industrial city 250 miles east of here where Sakharov has lived in internal exile since January 1980.

Bonner said she suffered a heart attack on April 25 and both she and Sakharov wanted to be admitted to an Academy of Sciences heart clinic here because it was the only hospital in which they would feel safe. Sakharov will be 62 Saturday; his wife is two years younger.

There was speculation last month that Moscow was preparing to allow Sakharov to leave the Soviet Union after Justice Minister Vladimir Terebilov said in an interview with Swedish television that "there would be no obstacles" should the physicist wish to emigrate.

A subsequent statement by the official news agency Tass, however, asserted that Sakharov would not be allowed to leave because he knew state secrets. He helped develop the Soviet hydrogen bomb.

Hours before Tass issued its statement, Bonner had met with a group of western journalists and sharply denounced the Soviet authorities as "terrorists" and compared them with the Italian Red Brigades. Some observers here speculate that her remarks angered the Kremlin leadership and diminished chances for Sakharov to leave.

In her comments today, Bonner accused Soviet authorities of isolating Sakharov in Gorki to plot his premature demise. In Gorki, she said, "doctors will be found to say that he died a nonviolent death."

Sitting on a window sill outside her building, Bonner said the clinic here had agreed last week to admit her for treatment but had turned down her request that Sakharov also be admitted.

"Our situation is a tragic one," she said. "I am begging for hospitalization together with my husband so he will not die. I cannot leave him alone for long; he suffers from severe heart problems and has already had two mild heart attacks.

"Today, I am asking for help with only a very small thing--to be allowed to lie in the hospital and sanatorium of the Academy of Sciences. And I ask for something to be done quickly because we are both ill."

Bonner said her husband, who won the Nobel Peace Prize for his human rights activities, would not undergo medical treatment in Gorki because he feared he would be "killed" while in the hospital. As a member of the Academy of Sciences, Sakharov is entitled to be treated in its clinic.

The unusual sidewalk press conference under the gaze of police and KGB agents coincided with a bitter public attack in the Communist Party newspaper Pravda on President Reagan's declaration of Sakharov's birthday Saturday as a day in his honor.

Pravda called it an insolent and hypocritcal move by a president "living in a fantasy world in which he believes he could force other countries to follow U.S. dictates on human rights." It described Sakharov as a "servant of American imperialism" and said Reagan's decision followed his proclamations of various other special days in his crusade against communism. Recalling that such days involved Poland, Afghanistan and Cuba, Pravda said, "Perhaps the day of common sense should be announced in the United States at least once a year."

Bonner, however, expressed "great gratitude to the U.S. government" for declaring Sakharov's birthday as a day in his honor.

Although Sakharov was given a four-room apartment, a luxury by Soviet standards, in Gorki and can use his automobile, he cannot receive visitors, telephone friends or receive mail.

Sakharov had earlier said that he would accept an offer to teach at the University of Vienna. Bonner said today she had been in touch with Norwegian diplomats regarding an offer from their government to settle in Norway. She said Sakharov would be happy to do so.

Friends of the Sakharovs here have said the physicist is finding his banishment less bearable because the absence of information was preventing him from continuing his work. Bonner reported last fall that Sakharov was drugged in his automobile and robbed of his manuscripts.

Bonner said Sakharov had written an appeal to Anatoly Alexandrov, the president of the Soviet Academy of Sciences, asking that he be allowed to enter the academy's clinic in Moscow. She said that he had not received a response but that there were indications that the answer would be negative.