BONN, JUNE 24 -- The United States is considering converting some medium-range nuclear missiles, which are to be removed from Europe in a planned disarmament treaty with Moscow, into shorter-range missiles which then could be given to West Germany, a senior U.S. arms negotiator said today.

Soviet officials recently said the United States was weighing such a plan and said it would stand in the way of the arms accord, but the idea had not been disclosed by the United States.

Washington may have floated the proposal as a kind of bargaining chip, U.S. and West German arms control experts said.

Maynard Glitman, chief U.S. negotiator for intermediate-range missiles in the Geneva arms talks, said his staff was studying whether it would be legal under the proposed treaty to convert Pershing II missiles to shorter-range Pershing IBs and then transfer them to West Germany. If West Germany agreed, the Pershing IBs would replace 72 outdated Pershing IA missiles that are owned by the West German Air Force but whose warheads are under U.S. control, Glitman said.

The United States would control the warheads for the Pershing IBs as it does for the Pershing IAs, Glitman said. He disclosed the proposal while responding to questions at an arms control workshop here sponsored by the Social Democratic Party.

Soviet Foreign Ministry arms expert Viktor Karpov said in an interview this month with the West German magazine Der Spiegel that the United States was considering giving such converted missiles to its NATO allies, including Italy, the Netherlands and Turkey.

The U.S. plan was designed to evade the planned arms treaty, which would ban the United States and Soviet Union from deploying such shorter-range missiles of their own, Karpov said. He suggested that the Soviet Union could do the same, giving shorter-range missiles to its Warsaw Pact allies.

Glitman denied that the United States would consider giving shorter-range missiles to any ally other than West Germany.

Glitman's statement seemed certain to sharpen the U.S.-Soviet dispute over the Pershing IAs. The missiles have a range of about 450 miles, and therefore fall in the category of shorter-range missiles to be withdrawn from Europe as part of the treaty.

The United States insists that the Pershing IAs are a West German system and therefore outside the scope of the bilateral, U.S.-Soviet talks at Geneva. The Soviets contend that the warheads for the Pershing IAs must be withdrawn as part of the deal because they are under U.S. control.

U.S. and West German disarmament experts suggested that Washington may agree in the end not to convert the Pershing IIs to Pershing IBs in exchange for Soviet acceptance of the continued presence of the West German Pershing IAs. In this view, the Soviets would be willing to allow the Pershing IAs to stay because they are expected to become obsolete in the early 1990s.