Sen. Charles H. Percy (R-Ill.), incoming chairman of the Senate Foreign Relations Committee, said yesterday he is confident on the basis of contacts in the two camps that the United States and the Soviet Union are willing to undertake talks on arms control and other matters early in the Reagan administration.

In an interview, Percy said Soviet President Leonid Brezhnev made clear to him in Moscow late last month that the Russians would like an early meeting at a high level with the Reagan team, and that Soviet officials have confirmed this to him since his return to Washington.

Percy said he has recommended such a session to President-elect Ronald Reagan's foreign policy advisers and is confident that such meetings will be approved unless events -- such as a Soviet invasion of Poland -- get in the way.

Sources close to Reagan said he remains ready for early discussions with the Soviets. On the basis of contacts between Soviet diplomats and members of the Reagan staff, the sources said, such talks seem likely in the absence of a roadblock due to Poland.

By referring to "talks" or "discussions" rather than "negotiations," Washington and Moscow appear to be seeking a way around the troublesome issue of SALT II, the strategic arms limitation treaty signed by President Carter and Brezhnev in June 1979 but which the Senate has never ratified.

Reagan opposed SALT II and proposed negotiations on a successor treaty incorporating some aspects of the earlier accord.

According to a Soviet official who recently visited Washington, Moscow's basic position is that there is no reason to reopen negotiations on strategic arms. The Soviet Union, while sticking to the SALT II bargain struck with the Carter administration, is willing to explore broad questions of arms control with the Reagan administration, the Soviet official said.

Percy said that if preliminary talks go well, he foresees a renewal of more formal and intensive arms talks. He said that he warned Brezhnev, however, that a Soviet invasion of Poland would destroy the chance for any new treaty of significance in his and Brezhnev's lifetime.

Percy's discussions in Moscow on arms control and the Middle East were the subject of secret cables from the U.S. Embassy in Moscow that were leaked to The New York Times a week ago. The state Department confirmed yesterday that it has asked the FBI to investigate the leak. Spokesman Jack Cannon said the department made the request early this week after being asked to do so by Percy and Sen. Jesse Helms (R-N.C.), another senior member of the Foreign Relations Committee.

Helm's interest stems partly from a charge published in The Washington Star that the leak came from John Carbaugh, his foreign policy aide. Carbaugh has denied the charge and offered to take a lie-detector test.

Senate meetings over the past few days have determined the membership of the Foreign Relations Committee in the new Congress, and subcommittee chairmanships were handed out to committee Republicans in a meeting Thursday. The new subcommittee chairmen are:

Latin America -- Helms, a leading opponent of the Panama Canal treaties and of the Carter administration's policy of working with reformist, sometimes radical groups.

Middle East and South Asia -- Rudy Boschwitz (Minn.), a German-born Jewish refugee who is a strong backer of Israel.

Europe -- Richard G. Lugar (Ind.), who studied in England as a Rhodes Scholar.

Africa -- Nancy Landon Kassebaum (Kan.), who has no experience with Africa but who holds a master of arts degree in diplomatic history.

Asia -- S. I. Hayakawa (Calif.), an educator and semanticist of Japanese extraction.

International Economic Affairs -- Charles McC. Mathias (Md.), who has expressed consistent interest in foreign affairs, though not previously a member of the Foreign Relations Committee.

Arms Control -- Larry Pressler (S.D.), an Army lieutenant in Vietnam.

Boschwitz, Kassebaum, Mathias and Pressler are new Republican members of the committee. The new Democratic members are Alan Cranston (Calif.), the Senate Democratic whip, and Christopher J. Dodd (Conn.).