Soviet autorities today reportedly imposed a July 25 deadline for the wife of exiled disident leader Alexander Ginzburg to decide whether she will leave the Soviet Union with her immediate family, or lose the right to join her husband in the United States.

A senior Soviet emigration official reportedly told Arina Ginzburg that the family's unofficially adopted son, Sergei Shibayev, whom she wants to take with her, will "never" leave the Soviet Union.

The issue of the release of Shibayev, 19, who lived with the family almost five years and now is an army draftee, has stalled the family's departure since April 27, when Alexander Ginzburg and four other political prisoners were exchanged for two Soviets convicted of spying in the United States.

The swap worked out by the White House and Soviet Ambassador Anatoliy Dobrynin included the dissidents' immediate families. The Soviets allowed the niece of one dissident to leave, but have balked at Shibayev on grounds he was never legally adopted by the Ginzburgs.

In Washington a senior administration official said the United States has not been officially notified of any Soviet decision regarding Shibayev. "We've interested in the case and we hope they'll give it favorable consideration," said Jerrold Schecter, spokesman for the National Security Council "We hope human compassion will play a role in their determination."

It was understood in Washington that the U.S. government still hopes for a favorable resolution of the matter and has not decided how to react if Shibayev is not permitted to leave with Mrs. Ginzburg, partly because of Shibayev's uncertain status under Soviet law.

Mrs. Ginzburg said she was told by emigration official Vasili Gerasimov in a brief, contentious meeting today that "it is the decision of the secret police, the Foreign Ministry and the Interior Ministry" that Shibayer will not be granted exit status, "not now, not after the army, not ever."

She said Gerasimov gave her until July 25 to inform the Interior Ministry's visa department that she intends to emigrate with her family, "If you don't answer, your case is closed and you cannot go," Gerasimov warned her, she said. After that, he reportedly said, her only possibility of emigrating would be to apply for an exit visa to Israel, a process that could lead to further delays.

The immediate families of the other four political prisoners - Georgi Vins, Eduard Kuznetsov, Mark Dymshits and Valentin Moroz - have left in recent weeks.

Shibayev has said he wants to emigrate and Mrs. Ginzburg says she cannot leave him behind because she fears reprisals against him. Shibayev, neglected by an alcoholic mother, was drafted last year even though he has a leg deformity from childhood. Dissidents say the call up was an official reprisal because he refused to testify against Ginzburg at his trial last summer.

Mrs. Ginzburg said Gerasimov refused to give her any information on Shibayev's wherabouts or condition. He was sent to duty in the rigorous Siberian northeast.

The Soviet press agency Tass recently denounced Shibayev as a "pseudo-son" of the Ginzburgs, saying his emigration would not reunite "a mythical family, but break up a real one."

Meanwhile, the wife of imprisoned dissident figure Yuri Orlov said today the Soviets have prevented meetings between lawyers for her husband and another jailed dissident, Sergei Kovalyov, by threatening personal searches of the lawyers.

Other dissidents said the collegium of Moscow lawyers, in an unusual move, officially objected to the Interior Ministry over these tactics, but their letter was rejected.