Egon Bahr, a leading figure on the left wing of West Germany's ruling Social Democratic Party, claims that Soviet President Leonid Brezhnev actually has "opened the door wide to negotiations" on reducing medium-range, nuclear-tipped rockets in Central Europe.

In a major address in East Berlin last weekend that has stirred considerable international controversy, the Kremlin leader offered to reduce the number of such missiles already deployed by the Soviets and aimed at Western Europe if the NATO alliance refrained from deploying similar missiles in Europe.

Brezhnev's offer has been greeted with skepticism in Washington and in a number West European circles because it is seen as an attempt by the Soviets to maintain their already sizable edge in these quick-strike weapons while keeping NATO from fielding weapons able to balance the Soviet arms.

The NATO defense ministers are expected to approve a plan during a meeting in December, which will authorize production of U.S. bases in Britain, West Germany, Belgium, Holland and Italy. The plan also calls for a corresponding NATO arms control offer meant to allow the West to discuss eventual missile reductions with the Soviets. But the discussions would be held while production was going ahead.

Bahr, however, in a discussion with West German journalists here, called attention to the phrasing of Brezhnev's offer, in which the Soviet chief raised strong objections to the "stationing" of those new missiles in Western Europe, but did not refer to decisions about production. Bahr argues that the soviet chief, therefore, left room for a NATO decision to begin production that still would not necessarily disrupt East-West relations.

The significance of Bahr's comments lie in two areas.

Among West German political figures, Bahr, along with Social Democratic Party chairman Willy Brandt, has the closet contacts with the Soviet hierarchy and thus may well be reflecting further soviet emphasis on Brezhnev's meaning.

Secondly, as a leading figure and thinker of the party's left, Bahr is precisely the type if figure that many Western officials believe the Soviets will lean on to turn public opinion in Western Europe toward the Soviet view.

A spokesman for West German Chancellor Helmut Schmidt said tonight that Schmidt and the Bonn government did not share Bahr's view of a production-only NATO decision and that the government's position here in support of the NATO plan had not changed. Officials here privately suggested Bahr also might modify his comments soon.