A man identified as the top Soviet interpreter at East-West troop reduction talks in vienna has defected to West Germany, reportedly with secret Soviet negotiating documents, it was reported today.

A government spokesman here refused to disclose details of the defection, saying only that "the government is aware that a Soviet citizen, Nikolai Korolyuk, has arrived in the Federal Republic of [West] Germany." Other sources identified the man as Viktor Korolyuk, 35, who translated from Russian into German. He reportedly had been in ; Vienna for varying periods during the last two years.

The spokesman indicated that the defection was a highly delicate development in the stalled eight-year-old Mutual and Balanced Force Reduction talks in Vienna.

"We ask our understanding that additional details cannot be disclosed at this time," the spokesman said.

He refused to comment on a report that the defector brought with him a packet of Soviet negotiating documents. Speculation here suggested that the documents might provide useful information on the key issue blocking progress in the troop reduction talks -- the actual number of Soviet troops in Central Europe. According to Western intelligence sources, there are about 150,000 more Soviet troops in the area than Moscow admits having there.

The defection was disclosed earlier today by the Stuttgarter Zeiting in a dispatch from Vienna. The newspaper described Korolyuk as the chief interpreter for Soviet delegation, a position that might have made him privy to details of the Soviet negotiating stance, according to some sources here.

According to the Stuttgarter Zeitung, the interpreter slipped unnoticed out of the Soviet delegation's hotel in Baden, south of Vienna, about three weeks ago as the talks recessed for Christmas.

He went to Vienna's Schwechat Airport and boarded the first plane headed to a Western country from neutral Austria. The plane took him to Dusseldorf, where he turned himself in to airport police who notified the federal intelligence agency. The defector was reportedly taken then to a secret location. The government spokesman refused to pinpoint his whereabouts.

The Soviet Embassy in Vienna refused to comment on the reported defection. It said that the Soviet delegation returned to Moscow on Dec. 20 after a Christmas holiday break in the talks.

The delegation is due to return to Vienna on Jan. 20. The latest round of the talks ended Dec. 18 with no sign of a break in the deadlock.