A leader of the Soviet arms control negotiating team said today that a ban on space weapons research -- defined by Moscow as the key to progress in the Geneva nuclear arms talks -- can be verified.

The U.S. government has argued that research on such weapons is going on in both countries and that work in laboratories and other facilities cannot be verified adequately to ensure compliance with agreements.

Soviet arms delegate Yuli Kvitsinsky said Moscow's position was "not aimed at banning fundamental research." Instead, he said it was aimed at banning what he called "purposeful and directed research" on space weaponry.

"Work on space weapons, even at an early stage, is accompanied by the emergence of particular distinguishing signs," he said. These signs, he added, could be identified by "national technical means," a term used to describe surveillance by satellites of each nation.

Speaking at a press conference, Kvitsinsky's remarks appeared to be an effort to clarify what the Soviets see as the acceptable threshold for research into space-based defense systems.

Today's press conference was called to focus attention on the Reagan administration's "Star Wars" program or Strategic Defense Initiative (SDI), which the Soviets say is the obstacle at the Geneva talks.

"What is involved here is not pure science," said Kvitsinksy of the U.S. project, noting that the Soviet position would not affect scientists "looking at the firmament and figuring out what to do to defend" a continent.

At the same press conference, a spokesman for the Soviet military confirmed two high-level changes at the Defense Ministry.

But Gen. Nikolai Chervov would neither confirm nor deny that Marshal Nikolai Ogarkov, ousted as chief of staff last September, has been reassigned as commander of Warsaw Pact forces, as reported last week. "We have no such information," said Chervov.

The Ogarkov appointment, restoring the 67-year-old marshal to a high position in the military after spending 10 months in obscurity, is the most significant of the reported shifts. According to the reports, Ogarkov would replace Viktor Kulikov at the Warsaw Pact headquarters.

Chervov said Marshal Vladimir Tolubko, 70, chief of strategic forces since 1972, and Marshal Alexei Yepishev, 77, for 20 years the head of the military's political directorate, had moved out of their jobs.

Yepishev has been replaced by Alexei Lizichev, a 57-year-old general who has served as head of the political department with Soviet forces in East Germany. No one has been named to succeed Tolubko yet, Chervov said.

While Chervov was vague about appointments, he voiced strong feelings about SDI.

"SDI is not a needle in a haystack that is impossible to find," he said, although he noted that 90 percent of any military program involves research and development.

The Soviets have acknowleged a research program into laser technology and other areas associated with their own program, but say their efforts are not designed for "space strike weapons."

Chervov also repeated the Soviet position that if SDI goes forward, the Soviets will respond with "countermeasures," although not necessarily with a copy of the American program.