Prime Minister Andreas Papandreou today became the first West European government leader to give official backing to the antinuclear peace movement.

In an hour-long speech opening a conference on nuclear-free zones in Europe, Papandreou called on all West European governments to support the nuclear disarmament movement.

"This is the only mechanism for halting a course toward disaster that I can see," he said. "Peace movements should stop being opposed on the pretext that they are being financed by the East Bloc."

The Socialist leader stated his own government's opposition to the deployment of U.S. medium-range Pershing II and cruise missiles in Europe. He said Greece supports the U.S. "zero option" proposal under which the Pershing and cruise deployment would be halted if Moscow dismantled its 300-plus SS20 missiles targeted on Western Europe.

Papandreou contended in his speech that nuclear-free zones in Europe could serve as a starting point for a general nuclear disarmament accord. He said Greece has started talks with Romania, Bulgaria and Yugoslavia on a Balkan nuclear-free zone and that procedures could be completed in one year.

"We have decided we need six months of contacts on the level of foreign undersecretary, six months on the level of foreign ministers, and then we could hold a summit before going ahead," he said.

Papandreou also reiterated his government's view that removing nuclear weapons from Greece is not linked to the future of the U.S. military bases here.

Talks on the future of the bases, which the Greek government wants phased out, are currently going on in Athens. The bases were established under a U.S.-Greek treaty in 1953. Nuclear weapons were placed in Greece under a separate agreement in 1959. They include nuclear mines deployed on the Balkan border and Honest John missiles, which date from the 1950s and which experts describe as "outmoded but usable."

The three-day conference here has drawn delegates from the major West European as well as Balkan peace movements. According to the Movement for National Independence, World Peace and Disarmament, organizers of the conference, observers also had been invited from other East Bloc countries, including the Soviet Union, but none had appeared by this morning's opening session.