The International Olympic Committee (IOC) today rejected a U.S. proposal that this summer's Olympic Games be moved from Moscow, postponed or canceled in response to the Soviet invasion of Afghanistan, but indicated it might reconsider if a substantial number of countries decide not to send their athletes to Moscow.

IOC President Lord Killanin issued a carefully worded, 14-paragraph statement that he said had been approved "unanimously," but without a formal vote, by the 73 IOC members meeting in full session before the Winter Olympics begin here Wednesday.

The IOC said in the statement that the Summer Games "must be held in Moscow as planned" and that "all preparations have been made in keeping with the terms" of the agreement between the IOC and the Moscow Olympic Organizing Committee and "consistent with the rules of the IOC."

The IOC thus rejected the legal argument presented by the U.S. Olympic Committee (USOC), and endorsed by the U.S. government, that the Soviet agression in Afghanistan constituted an abrogation of Moscow's contract for hosting the Games.

In a news conference, Killanin emphasized that the national committees are not required to respond to invitations to the Moscow Games until May 24, and that "they must have time to think over" the question of participation. 2The implication was that the IOC hopes that the Soviet Union has withdrawn enough troops from Afghanistan by May 24 that Western and Third-World nations will decide to send athletes to Moscow.

Killanin also said that the IOC "wuld keep all options open," including reopening deliberations if it appears that a substantial number of countries do not intend to send teams to Moscow.

"The Games will be held . . . Killanin said. ". . . We hope the majority of national olympic committees will decide to go. I think it would be very sad if they all came from any one political aspect, but I don't think that will happen."

Asked if the IOC would reconsider today's decision if as many as 30 nations, including the United States and its major allies, expressed intent to reject invitations, Killanin said:

"That is one of the reasons I said I would keep all options open. We have not arranged for a special session, and I wouldn't put a figure on it [the number of countries], but if the situations change, then I think that it is a possibility."

The IOC statement obliquely chastised the Soviet Union for its aggression by urging the Moscow organizing committee and the Soviet Olympic Committee "to inform the highest authorities of their government of the circumstances which have created these difficulties" -- that is, the reluctance of so many nations to participate in Games in Moscow.

IOC sources also said today that they had "received signals" from the Carter administration that it will not necessarily request that the USOC not attend the Moscow Games unless Soviet troops are "fully withdrawn" from Afghanistan by Feb. 20, the deadline and conditions previously set by President Carter.

The sources said it was their understanding that the administration would consider supporting the participation of American athletes if there were a substantial withdrawal of Soviet troops by the May 24 deadline for accepting an invitation to the Games.

White House press secretary Jody Powell today said there has been no change in the Feb. 20 deadline for "full withdrawal," and that presidential counsel Lloyd Cutler spoke without authorization Monday when he said that a significant withdrawal of Soviet troops between Feb. 20 and May 24 "would have to be considered" as an acceptable basis for U.S. participation in Moscow.

Cutler told The Washington Post on Monday: "If there were a bona fide withdrawal, or a plan for a bona fide withdrawal, it would have to be considered. After all, the objective of this is not to inflict a punishment but to achieve a result."

Powell, asked to comment on Cutler's statement, said: "That's wrong . . . Our position is as it was. As of Feb. 20, if they're not out of there, the president will not support, nor does he believe the American people would support, sending a team to Moscow."

IOC officials believe that Cutler's statement is closer to the administration's intentions, and that, if Soviet troops are withdrawn by May 24, Carter will not insist that the USOC not send a team to Moscow.

One IOC source said privately that Killanin believes it is up to the Soviet government to determine how many nations will participate in Moscow, and ultimately whether there will be Games there this summer, by the course it takes in Afghanistan in the next three months.

Meanwhile, in a unanimous ruling, the New York Court of Appeals refused to strike down an IOC rule barring the team from Taiwan from competing under the flag and anthem of the Republic of China. On Monday, the Appellate Division of the New York Supreme Court upheld the rule, which was designed to allow the People's Republic of China to participate in its first Olympics.

The IOC rule requires the Taiwan athletes to call themselves Taiwanese and use the flag of the Olympic committee. The Taiwanese have refused to do so.