World chess champin Anatoly Karpov and his No. 1 rival Victor Korchnoi may have their next encounter in April in Washington, D.C. The legendry Bobby Fischer has also been invited to join the planned World Cup Tournament, but hasn't answered yet.

Karpov said in a recent interview in a Soviet newspaper that the Washington tournament "will probably be my next official appearance," but Korchnoi doubts it. Karpov will not play, Korchnoi said recently because =he is afraid of me" and "the Soviets boycott me."

Earlier thes year, Karpov held on to his championship by a margin of one point in a cliff-hanging 32 game match with Korchnoi. If tournament organizer Ilya Chamberlain has his way, the pair will meet again here in a glassenclosed isolation booth with 10 of the world's other leading players also fighting it out, and giant electronec desplay boards to show fans the progress of the games.

A boycott by the Russians would eliminate not only Karpov -- who this week was named Soviet sportman of the year by the Federation of Sovit Sports Journalists -- but probsnly also former world champion Boris Spassky, and would seriously damage the tournament's strength.

Chamberlain has sent invitations to both Russian players but has not yet received a written reply from either. In answer to an oral invitation, transmitted by U.S. champion Lubomir Kavalek, Karpov tentatively accepted and said that "it would make no differnce" whether Korchnoi played or not.

Chamberlain, who arranged the Volvo Cup match between Kavalek Volvo Cup match between Kavalek and Sweden's leding player Ulf Anderson in Washington earlier this year, says he has already raised more than $400,000 to finance the match from private citizens and corporate and governmental sources on three continents.

"I plan to raise another $200,000, so that we can do it right," he added.

Chamberlain is a retired biochemist who receives royalities fron patents on a soybean fermentation process. A native of London, he taught at Oxford and was for four years a vice president of a major American food-processing company.

In his retirement, Chamberlain passes his time selling Volvos to members of the diplomatic corps in Wshington, a job in which hes speaking knowledge of foreign languages (incllding Russian, Japanese, German, Italian, French, Spanish and Portuguese) has been helpful. "I don't know any selling techniques," Chamberlain says. "I sell the cars, but it's not because I know how to sell cars, it's because I listen to people -- in their own language."

Chamberlain has not sent out all the invitations yet, pending publication of the next official standings of the world's top players. The list, pubished at the beginning of the year by the International Chess Federation, will probably determine who receives the invitation in a few borderline cases. Among those who are certain to be in the top 12, Chamberlain has received acceptances from Korchnoi, Bent Larsen, Lajos Portisch and henrique Mecking, all of whom were quarter-finalists in the recent world championship.

"Fischer hasn't answered yet," Chamberlain sais, "but I only sint the invitation a few days ago, I hesitated a long time, but after a talk with his friend and mentor John Collins, I decided to try to get him,"

Fischer nas not played in public since winning the world championship in 1972, but he is scheduled to come out of retirement in March with a match in Yugoslavia. Since he has been promised a prize of $1 million for that match, win or lose, the $15,000 top-prize money of the Washington tournament may not interest him. But he and Karpov are reportedly both eager to play one another and Washington provides the earliest opportunity.

The tournament will be a double round robin, which means that they would play two games, each having white and balck once. Karpov and Fischer have begun negotiations for a match several times, including a series of discussions in Washington when Karpov gave a simultaneous exhibition here last year, but they have never been able to reach mutually agreeable terms.

Chamberlain's top prize of $15,000 is considerably higher than those given in most international tournaments, and each of the participarting players will receive a $2,000 appearance fee puls all expenses.

"I am inviting the world's best players to paticipate in this tournament," Chamberlain said. "If the Russians make it impossible for some of them to play, they had better be ready for a storm of international protest about the way they play politics with chess."

Reached by telephone at his home in Switzerland, Korchnoi repeated the charge that the Russians are boycotting him and said that it is part of what used to be a general policy. In recent years, some of Rissia's leading chess players have joined the writers, musicians, ballet dancers and ordinary citizens who have been leaving the Soviet Union, and the boycotts were a response to this trend, Korchnoi said.

"When the first masters and grandmasters began to apply for visas," Korchnoi said, "the Soviets did not know what to do. They began to boycott them from 1972 to 1974, but they don't do it anymore because there are too many. They cannot boycott every competition."

Since Korchnoi defected from the Soviet Union in July 1976, Russian players have in fact refused to participate in events that included him except for the world individual and team championships.In the preliminary rounds of the world champion-ship, the Soviet Chess Federation tried to have him disqualified because he was stateless, and then threatened not to let Russians play against him. This tactic was abandoned when they were told that Korchnoi would win by forfeit if his opponents refused to play.

The most successful boycott was that against Czech grandmaster Ludek Pachmann, who supported the Dubcek regime in 1968 and was imprisoned and later exiled from Czechoslovakia because of his political activities.

Since his emigration to West Germany, Pachmann's career as an international-level player has been effectively destroyed because players from Russia and other Eastern European countries boycott tournaments in which he plays. Outside of a few small international tournaments which did not feel the need of Russian participation, he has played mostly in the German national chess league and has supported himself partly by publishing books and articles on chess theory.

In his autobiography, "Checkmate in Prague," he made a charge also made in Korchnoi's autobiography, "Chess Is My Life": that the chess bureaucracy in Iron Curtain countries sometimes rigs the results of chess events for the benefit of players favored for ideological or other reasons.

Comparing his treatment with Pachmann's, Korchnoi said in the phone interview that there is not an exact parallel because Pachmann had been a pllitical figure as well as a leading chess player.

"I was not political," Korchnoi said. "When I left the Soviet Union, I was a chess player trying to find the best circumstances to advance my career. Now, I am more or less dissident, but then I was not dissident. I have had dissidence forced upon me by the way the Soviet Union acted in this situation."