A top Soviet diplomat said today that the Soviet Union's recent arms control proposal, calling for a 50 percent cut in strategic weapons on both sides, is not a final offer.

Speaking at a news conference to Soviet and foreign journalists, First Deputy Foreign Minister Georgi Kornienko added that the next move at the negotiating table in Geneva is up to the United States.

"We do not take such approaches as 'zero option' or 'take it or leave it,' " said Kornienko.

"The answer [to the Soviet proposal] should be constructive, and we will not be found wanting." Kornienko shared the podium today with the chief of the Soviet general staff, Sergei Akhromeyev, and Kremlin chief spokesman Leonid Zamyatin.

Few new details of the Soviet proposal in Geneva emerged today, although Akhromeyev did indicate that the Soviet proposal on medium-range weapons in Europe envisons the removal of the 81 Pershing II missiles deployed by the North Atlantic Treaty Organization.

"We propose that the American missiles should be cut -- both Pershing and cruise missiles -- and that the NATO countries should maintain only French and British missiles," he said, adding that the Soviet force then would be equal to the independent French and British arsenals combined.

"This is no injustice," he said. "An equal number of missiles and warheads would belong to both sides. But we say no to Pershings."

Zamyatin also reported today that Marshal Nikolai Ogarkov, the former chief of staff who was ousted from the job in September 1984, is "in a responsible position in the Defense Ministry" and "continues to work as successfully as before."