Soviet threat on START reported

The Soviet Union is threatening to halt negotiations on reducing long-range nuclear weapons if the United States deploys new medium-range missiles in Europe as scheduled, it was reported Thursday.

According to CBS News and the Washington Post, informed sources said the Soviets threatened to pull out of the arms control talks in Geneva if the missiles are put in place as planned.

If even one new Pershing II or cruise missile were deployed in Western Europe the START talks would come to a halt, the sources were quoted as saying. The Soviet Union had thus made the talks ''hostage'' to the parallel intermediate-range nuclear force (INF) negotiations that resume in Geneva soon, according to a Post source. The Soviets' message reportedly came during the second round of the strategic arms reduction talks (START) in Geneva last November.

The newspaper quoted anonymous sources as saying the threat to quit the negotiations shows how far the Soviets are willing to go in building diplomatic and political pressure to prevent deployment of the new missiles.

The official Soviet news agency Tass said Thursday that Moscow rejected a so-called intermediate agreement on medium-range missiles in Europe. Such an agreement, as suggested by several European politicians, calls for cuts in Soviet medium-range missiles in return for the deployment by NATO of fewer than its planned 572 cruise and Pershing II missiles in Europe, the journal said.

In Washington Thursday, President Reagan said the overriding Soviet goal was to prevent deployment of even a single medium-range US nuclear missile in Europe.

In East Berlin, Soviet Foreign Minister Andrei Gromyko appealed to West Germany to reconsider carefully its decision to deploy new US nuclear missiles this year.