West German Chancellor Helmut Schmidt said in a television interview last night that Soviet President Leonid Brezhnev, during his visit here last week, indicated a willingness to negotiate with the West over weapons in the so-called "gray area", of atomic weaponry.

Schmidt gave medium-range missiles as "an example" of such weapons.

The recent deployment by the Soviets of nuclear-tipped intermediate-range SS-20 missiles targeted on Western Europe is a major concern within the North Atlantic alliance and both the United States and NATO have been pressing the Soviets to cut back on these weapons.

Schmidt's remarks seemed to indicate for the first time that the Soviets would be prepared to negotiate over such weapons but other high-level sources here said they were "dubious" about how much Brezhnev's reported willingness to talk really means.

The gray-area weapons are those that lie outside the two major negotiating forums for arms control. The U.S.-Soviet talks on strategic arms limitation deal with ocean-spanning bombers talks in missiles. The troop reduction talks in Vienna, between NATO and the Warsaw Pact, deal with reductions of East-West ground forces.

The gray area weapons have taken on considerable importance in the past year because they could include not only the SS-20 but also, depending upon whose view is accepted, the new Soviet Backfire bomber and the new U.S.-developed neutron weapon. These new developments stand in the way of further efforts to control atomic armaments.

Schmidt described the Soviet's "expressed . . . readiness to negotiate over weapons in the gray zone" as a "step forward." He said he was able to assure both Brezhnev and, President Carter, when he telephoned later, that both leaders were intent upon bringing about peace.

Other sources here informed about the private Schmidt-Brezhnev talks painted a somewhat less enthusiastic picture.

In their description, the West Germans suggested that it would be a good idea to discuss these gray-area weapons and Brezhnev gave only a simple agreement but did not elaborate or say anything about the forum in which these discussions might take place.

"The fact that he didn't object is of interest," one high-level source said, "but it is still very imprecise and what it may mean for the future we don't know."

Informed sources here also say that there was apparently no private discussion of the neutron weapon.

Carter has deferred a decision to produce these weapons pending signs that the Soviets will show restraint in their weapons buildup. The White House and Pentagon seem especially interested in Soviet restraint on SS-20 deployment or on pullbacks of some of their tank armies from Eastern Europe in return for a U.S. pledge not to build the neutron weapons.

Soviet spokesman Leonid Zamyatin, however, indicated at a press conference here last week that the Kremlin would not give up any of its conventional forces or rocketry in Europe in return for the U.S. neutron bomb pledge. He insisted that the weapon was one of mass destruction that should be outlawed - without conditions - under a new proposal Moscow will make later this month at the United Nations.