Twenty Soviet scholars here for a year of study at U.S. universities have been ordered home by their government on the grounds that anti-Soviet feeling caused by the shooting-down of a Korean jetliner could expose them to danger.

The scholars came under an exchange arrangement that has a similar number of American academicians working in the Soviet Union. The abrupt recall is the first such incident in the 25 years that the two countries have conducted such exchanges, and State Department officials said yesterday that when they leave there will be no Soviet citizens in this country under long-term exchange agreements.

A spokesman for the Soviet Embassy here said the action was being taken because of concern that in the present atmosphere of U.S.-Soviet recriminations the scholars might be subjected to harassment, intimidation and physical abuse.

The spokesman stressed that the recall of the scholars was not intended as retaliation for the sanctions the United States has sought to impose against the Soviets for the death of 269 persons on the Boeing 747 jet. It was shot down by Soviet fighters on Sept. 1 after it strayed into Soviet air space over Sakhalin Island north of the Sea of Japan.

Those Americans who have gone to Soviet universities and research institutes under the current exchange are welcome to remain there, the Soviet spokesman said. He also said it was possible that all or some of the 20 Soviets being recalled might return to the United States later in the academic year if "there is an improvement in the atmosphere."

State Department officials declined comment on the Soviet action. They added that the matter was being handled by the International Research and Exchange Board (IREX), a New York-based, private, nonprofit organization that administers scholarly exchanges with eastern European countries for the U.S. Information Agency and a consortium of 110 American universities. Daniel Matuszewski, associate director of IREX, said the Soviets had stressed to his organization that their decision to send the 20 home was dictated solely by security considerations.

He said the group of scholars had arrived in the United States shortly after the jetliner incident and had gone to the Soviet Embassy here for orientation before dispersing to various universities.

However, Matuszewski continued, he was informed by the embassy late Thursday that because of the intense feeling in the United States, and the attendant exchange of charges between Washington and Moscow, it had been decided that the security of the scholars could not be guaranteed once they were scattered around the country.

The two countries have been involved in a variety of academic, cultural and scientific exchanges since 1958. The most recent agreement under which they were conducted expired in 1979 and was not renewed as part of the U.S. protest against the Soviet invasion of Afghanistan.

Late last month, U.S. officials revealed that tentative plans were under way for negotiations on a new scientific and cultural exchange agreement, but that idea has been shelved, at least for now, because of rising tensions caused by the downing of the Korean plane. Despite the absence of a formal agreement, Washington and Moscow had been continuing what one official called "a handshake arrangement" for the exchange of from 20 to 45 scholars a year.

Matuszewski said that most of the Soviets involved were men in their 30s who hold teaching and research posts in Soviet universities or institutes for specialized studies. He said the majority of those who come here work in various natural science fields, although some are political scientists, economists or journalists.

He said that those who were to take part in this year's program were scheduled to go to approximately 14 universities, principally in the areas of Boston, New York, Washington, Chicago and San Francisco. But, he added, some would have been assigned to southern institutions like the Georgia Institute of Technology or to such Midwestern universities as Michigan and Wisconsin.

The embassy spokesman said the group is staying at the Soviet Embassy here while transportation is arranged. IREX officials said that because of the two-week boycott of Aeroflot, the Soviets probably would have to obtain permission for a special flight to come to the United States and pick up the scholars.