The Soviet Union sought today to break the deadlock at the marathon East-West talks on reducing armed forces in Central Europe with a proposal that appeared designed in part to address U.S. concerns about Moscow's geographical advantages.

Soviet Foreign Ministry spokesman Vladimir Lomeiko said the proposal was presented today in Vienna, where representatives of NATO and the Warsaw Pact have been discussing the issue for 11 years. He said the proposal calls on the United States to withdraw 13,000 U.S. troops from Central Europe while the Soviet Union would reduce its contingent in the area by 20,000 troops.

In Washington, the State Department "welcomed" the Soviet proposal, describing it as "a further development" in the Warsaw Pact's position in the Vienna talks. A spokesman said the United States and its NATO allies will study the proposal and respond in due course, adding, "We hope this move reflects a willingness to reestablish a serious dialogue in Vienna, which has been absent since the time NATO modified its position in April 1984."

The Soviet move came as the two superpowers prepared for the resumption of negotiations on strategic and intermediate-range nuclear weapons, as well as for new talks on space weapons and the Middle East.

Today's Soviet proposal also contained elements apparently designed to address western concerns about verification. Lomeiko said it included a provision for troops to pass through three or four designated observation points as they left the area covered by the talks -- West Germany, Belgium, the Netherlands and Luxembourg in the West, and East Germany, Poland and Czechoslovakia in the East.

Lomeiko said the proposal was a gesture of Soviet good will rather than acceptance of the idea of "compensation" for geographic advantages that the West has sought.

Western spokesmen have argued that the proximity of Soviet forces to the Central European theater gave Moscow additional advantages and insisted that the troop reductions would have to reflect that reality.

Lomeiko said the initial reductions, which would be carried out 12 months from the moment an agreement is reached on this issue, could be followed by larger cutbacks to reach a ceiling of 900,000 soldiers for each side in the Central European theater. He said that 50 percent of the Warsaw Pact reductions would involve Soviet troops.

The Soviet initiative at the 19-nation conference appeared designed to skirt the issue of the two sides' conflicting troop level estimates. The western side had been insisting on first agreeing on the existing troop levels, arguing that the Soviet Bloc was underestimating its troop concentrations in the theater by nearly 200,000.

Lomeiko vigorously denied the western assessments of the Soviet Bloc's troop concentrations, saying they were not substantiated by any credible evidence.

But, he continued, the Soviet proposal was designed to create a better climate. "The time has come," he said, "to get out of this dead end over figures. The way out, the way to cut through this fruitless discussion about who has more than who is to agree on a general collective [troop] ceiling."

Washington Post staff writer Don Oberdorfer added:

The Soviet proposal, according to State Department sources, picks up some elements of previous U.S. positions and thus represents some narrowing of the large gaps between the two sides. Specifically, the Soviets have agreed to incorporate their proposed reductions into a treaty, as the United States had asked, and to make most of the U.S. and Soviet reductions in identifiable combat units as Washington proposed.

The verification features also seem to represent some advance in the Soviet position, the sources said.

The problem of troop level estimates, or "data base," which has been a sticking point in the talks, has not been solved by the Soviet proposal, U.S. officials said.