The international Olympic Committee ruled out today the possibility of individual participation in this summer's Olympic Games in Moscow by athletes of countries whose national Olympic committees are boycotting the games.

In a press conference, following the last scheduled meeting of the executive board until the week before the troubled Moscow games, IOC President Lord Killanin of Ireland said the possibility of accepting individual entries had been discussed and rejected.

The Olympic committees of 30 countries, according to a revised tabulation, have declined invitations to the July 19-Aug. 3 Moscow games. Many of these -- including the United States, West Germany, Japan, Canada and China -- rejected invitations because of the Soviet invasion of Afghanistan and subsequent calls by the U.S. for a boycott.

Eighty-four national Olympic committees, including most of those of Western Europe, have accepted invitations. However, many Western countries will send smaller delegations than originally planned and will not not compete in certain sports.

Some individual athletes and sports federations in countries whose Olympic committees turned down the general invitation wished to compete in Moscow on their own, but this would have required a change in IOC rules.

Most national Olympic committees strongly opposed such a change, which would have undermined their authority. "The executive board discussed this question, and felt that it must stand by national Olympic committees," Killanin said today.

In a related development, the IOC has indicated that countries that submitted entries in various sports by the May 24 deadline and subsequently withdraw, will not be subject to penalties as long as their withdrawal takes place more than 10 days before competition begins.

This decision could pave the way for countries whose Olympic committees voted narrowly to accept invitations to Moscow -- notably Australia and New Zealand -- to reconsider their decisions and officially join the boycott.

Athletes and sports federations in those countries have been under heavy political pressure not to go to Moscow, and most have withdrawn, even though the general invitation was accepted. For example, only four New Zealand athletes from a delegation of about 100 are still planning to compete in Moscow.

On the other hand, Killanin said today that the IOC might accept entries in nonteam sports from countries whose national Olympic committees declined invitations but change their minds between now and July 9, even though the entry deadline was May 24.

In a wide-ranging briefing that followed two days of closed meetings at IOC headquarters here, Killanin said that the IOC's full session and election of a new president would take place in Moscow the week before the Games, as scheduled, that the IOC is not bankrupt, and the lowered standard of competition in Moscow because of the boycott is "a fact of life . . . that we have to accept."

IOC member Arpad Csanadi of Hungary, an expert on the technical aspect of the Olympics, gave an updated census of the countries that will participate in each sport.

The only sport that currently does not have enough entries for a meaningful competition, he said, was field hockey, in which only four nations (U.S.S.R., India, Spain, Holland) have entered the men's tournament and only one (U.S.S.R.) has entered the women's.

The international sports federations, which govern the Olympic sports, have selected replacements for countries that had qualified in team sports but will not go to Moscow, he said. A full complement of teams already has been selected in every sport except soccer, where one African team must be chosen to replace Ghana, and women's volleyball, where one place in the eight-team tournament remains to be filled.

Full contingents of teams will compete in gymnastics, water polo, modern pentathlon, men's and women's volleyball, men's and women's basketball, and soccer, even though some of the strongest teams will be absent in each of these sports.

Killanin said the effects of the boycott on various commercial contacts could not yet be calculated, but added: "I can assure you the IOC is not bankrupt, and we have agreed with the Moscow organizing committee that the IOC will pay for the transport of the judges, which number about 900. The organizing committee will accommodate them during the period they must be in Moscow."

Killanin told Thomas Keller, president of the General Association of International Sports Federations, that the IOC could not yet calculate what shares of television revenues each federation will receive from the IOC, but "at the worst, it will not be any less than four years ago."

Keler, who heads an increasingly influential branch of the Olympic family, told a reporter after his meeting with the executive board: "I am concerned about the future of the Olympic games, because I think the way they are handled now can no longer be accepted in the future from the viewpoint of the international federations.

"We collaborate fully (with the IOC), and now decisions are taken and not taken whereby the Games suffer tremendously. The Games cannot be attended by a lot of athletes, and they are no longer what they should be, but we have no influence on this at all."

Keller's comments were interpreted as a first shot in a battle for control of the Olympic movement in the wake of further East-West polarization of international sport caused by the Moscow boycott and its repercussions.

The international sports federations are expected to seek a larger role in Olympic decision-making in the future, and this could be a major issue at the Olympic Congress scheduled for Baden-Baden, West Germany, next year.