A new round of international speculation about the tense state of U.S.-Soviet relations was touched off yesterday by a news service report that Soviet Ambassador Anatoliy F. Dobrynin, dean of the Washington diplomatic corps, will be replaced this year.

Soviet specialists in and out of the Reagan administration expressed keen interest in the Reuter news agency report and said that, while there is no official confirmation, they would like to know if it was circulated by Soviet sources for ulterior purposes.

The report comes at a time of multiple shifts of Kremlin specialists in U.S. affairs and as the Soviet Union seeks to put maximum pressure on NATO allies to halt planned deployment of new U.S. nuclear missiles in western Europe in December.

Victor Isakov, a senior diplomat, arrived here last night to become a minister-counselor at the Soviet Embassy. He had been serving as a senior official in the American section of the Soviet foreign ministry.

Isakov replaces Alexander Bessmertnykh, who served as Dobrynin's deputy and left here last week to become head of the foreign ministry's American desk. Bessmertnykh replaced Viktor Komplektov, a new deputy foreign minister under Georgi M. Kornienko, first deputy to Foreign Minister Andrei A. Gromyko.

During the Cuban missile crisis in October, 1962, soon after Dobrynin's arrival in Washington, Kornienko was serving as Dobrynin's deputy here. There is speculation that he may be named to replace Dobrynin later this year or that the Kremlin may choose to send a less prominent successor.

Dobrynin, 63, has served 21 years here as ambassador. For years, there has been speculation that he would succeed Gromyko, 73, foreign minister since 1957, or be named to another high post in the Soviet hierarchy. Sources also have said he might be named a special adviser to the new Soviet party chief, Yuri V. Andropov.

Reuter said "a search is under way in Moscow for someone of stature to succeed Dobrynin when he leaves later this year," but added that " Dobrynin and Andropov . . . believe a less experienced diplomat could handle the job . . . basically one of carrying messages between the Kremlin and the State Department . . . . "

Reuter quoted one Soviet source as saying, "We don't need Dobrynin to report the views of Undersecretary of State Lawrence S. Eagleburger or Secretary of State George P. Shultz," because, in the current state of relations between the Kremlin and the Reagan administration, "there's hardly a relationship."

But the report also said that "The impending departure . . . reflected these realities rather than a decision by the Kremlin to downgrade ties with Washington or show displeasure over President Reagan's tough policies and anti-Soviet rhetoric."

State Department spokesman Alan Romberg said the administration has not been notified that the Soviet Union is planning for Dobrynin to leave. "I don't see the problem in communicating. Obviously, we have a variety of conversations going on with them . . . and we meet with Soviet officials here," Romberg said.

An embassy spokesman said, "We have no indication to prove this story." He added, "Certainly the ambassador is not packing."