Victor Korchnoi beat Boris Spassky yesterday in Belgrade, Yugoslavia, winning their match and securing his right to challenge world chess champion Anatoly Karpov later this year.

The end came rapidly in a position that had been adjourned from the day before. Referee Bodizar Kazic opened the envelope in which Spassky had sealed his 41st move overnight, pushed the white queen one square to QB3 and pressed the button to start Korchnoi's clock.

Spassky reached over and stopped the clock, indicating that the game was over and he had conceded defeat. Then he left the room without shaking hands with the winner, who had once been a close friend.

The final match score was 10 1/2 to 7 1/2 in Korchnoi's favor.

Besides the right to a return match against Karpov, who beat him by a single point in a 24-game match three years ago, Korchnoi won a $15,000 prize and a Yogoslavian-made automobile. Spassky's share of the purse was $10,000.

Relaxing with a cigar after the game, Korchnoi told reporters that Spassky's sealed move was a weak one that wouuld have resulted in a loss. Other continuations would have led to the draw that most experts had predicted, he said, but intensive analysis of the position overnight clearly convinced Spassky that after Q-B3 his position would be hopeless.

Korchnoi said that he is prepared to play Karpov for the world championship any time this year, possibly in August, and any place except the Soviet Union. He added that he hopes his wife and son, who were left behind in Leningrad when he defected from the Soviet Union in 1976, will be given exit visas to join him.

"Karpov is a damned good player," he remarked. "He is making progress every year and I must seriously prepare for the match."

His immediate plans include two tournaments in Holland and Israel, then a period of rest before he begins preparing for the Karpov match. Several countries have already made bids for the Korchnoi-Karpov match, including the Philippines, Italy, Switzerland, West Germany and Holland.