Soviet leader Yuri Andropov called today for an international agreement to ban the use of space weapons, saying "a crucial moment is really coming" to halt plans for moving the arms race into outer space.

"Either the interested states will sit down at the negotiating table without delay to begin drawing up a treaty prohibiting the deployment in space of weapons of any kind, or the arms race will go over also into space," Andropov said. The Soviet leader's remarks were contained in his reply to a telegram he received from a group of prominent Americans calling for a ban on space weapons.

The government news agency Tass said the telegram included signatures of Nobel prize laureates I.I. Rabi and Hans Bethe; retired admiral Noel Gayler, former head of the National Security Agency; Christopher Kraft, former director of the Johnson Space Center, and several prominent scientists.

It was the second time in three days that Andropov has responded personally to letters from Americans. On Monday he wrote to 10-year-old Samantha Smith of Manchester, Maine, who had expressed fears about nuclear war.

In Washington, State Department spokesman Alan Romberg said in response to Andropov's letter: "The Soviets possess the world's only operational antisatellite interceptor, which they continue to test." He added: "Other than a commitment to develop an antisatellite capability to match the Soviets, we are not planning any space weapons system."

Tass said the authors of the telegram appealed to Andropov and to President Reagan "to come to terms" on a pact banning the deployment of any kind of weapon in outer space as well as prohibiting "the damaging or destruction of the satellites of any state."

Although Andropov in his reply underscored Soviet readiness to negotiate a ban on space weapons, his warning that time was running out appeared designed to make it clear that the Soviet Union intended to match new U.S. space weapons systems.