It now appears likely that the United States Olympics Committee (USOC) will support President Carter's position that Americans should not participate in the 1980 Summer Olympics in Moscow unless Soviet troops are out of Afghanistan within four weeks.

USOC officials reiterated yesterday that it will be virtually impossible to persuade the International Olympic Committee (IOC) to relocate, postpone or cancel the games as the president urged in a television appearance and a firm, 750-word letter to USOC President Robert Kane.

The IOC, which owns the Olympics and contracts with local organizing committee to promote and stage them, reaffirmed its stand that the games will be held as scheduled in Moscow, July 19 through Aug. 3.

IOC President Lord Killanin acknowledged that a U.S. withdrawal "would be disastrous," but told United Press International from his home in Dublin: "It is legally and technically impossible to move the games from Moscow. It is not the business of the IOC to get involved in politics."

Kane and other USOC officials said yesterday that there is almost no hope of getting the IOC to change its position, but that the United States could choose not to send a team to Moscow without jeopardizing its status within the international Olymipic organization or American participation in future games.

"There is no nation within the Olympic movement, and no athlete, who has to go to the games," Kane told The Washington Post. "If for good reason -- domestic international, or whatever -- you do not wish to appear, all you have to do is notify the IOC. That would be working through proper channels."

In related developments, a spokesman for NBC-TV -- which has paid a total of $87 million for the rights and facilities to televise the Moscow games, and already has spent several million dollars in production costs -- said the network is "proceeding with the steps necessary to provide coverage" but will not televise the games if Americans do not participate.

The newspaper Sovietsky Sport, an authoritative voice of the Soviet government on sports matters, reported that Soviet athletes will not boycott the Winter Olympics at Lake Placid, N.Y., Feb. 13 through 24. And the chairman of the organizing committee for the 1984 Summer Olympics in Los Angeles voiced support of the president's position, although an American boycott of Moscow in 1980 could have serious repercussions on the 1984 games.

Kane said that the USOC's official position on compliance with the president's requests that an American team not go to Moscow unless Soviet troops are withdrawn from Afghanistan by Feb. 20 would be decided by the 86 voting members of the organization's executive board when they meet in Colorado Springs next weekend.

In the meantime, the USOC will do its best to poll some 10,000 prospective U.S. Olympic team members to get their opinions on withdrawing from the Moscow Games and related questions.

"We anticipate that somewhere around 550 American athletes would go to Moscow if we go, but there are about 10,000 candidates for the team in the various sports," said Kane. "That's the number of young men and women we're going to have to poll, as close as we could figure it.We're going to decide how to do that this week, but it's a hell of a big job.

A USOC staff member, called to the organization's Colorado Springs headquarters yesterday for an emergency briefing, said: "We don't even have a comprehensive list of the athletes likely to be invited to the Olympic trials in the various sports, much less a way to get a hold of them. I think we'll have to poll them through the national governing bodies of each sport, but I'm not sure. We'll have to work it out."

Kane and USOC Executive Director F. Don Miller issued a statement after a White House meeting with Secretary of State Cyrus R. Vance and other administration officials on Friday saying that the executive board would make a decision on entering American athletes in the games "based on the collective view of the athletes."

But at least one influential member of the executive board said he saw no alternative but to support President Carter's request, regardless of the athletes' views, and suggested that this would be the majority opionion of his colleagues as well.

"My reaction is, 'That's it.' If the Soviets aren't out of there in 30 days, we probably won't go . . . We certainly have to obey the command of our government and our president, I feel," said Douglas F. Roby of Ypsilanti, Mich., a past president of the USOC and one of two current American representatives on the IOC.

"I'm sure that the International Olympic Committee would not accept moving the games at this late date, or postponing them. The games would be canceled if they could not be held in Moscow, and that's very unlikely, in my opinion," said Roby, one of 79 voting members of the IOC.

Roby said that he and other members of the USOC and IOC "resented being drawn into this at first," and considered the president's initial mention of a possible Olympic boycott before consulting the USOC "an improper intrusion," but that he supports the president's action now that he was worked through Olympic channels.

"I think he's got to take some position, and if this is it, then I wouldn't criticize it," Roby said.

The other American on the IOC, Julian K. Roosevelt of New York, disagreed strongly, however.

"There were a lot of things the president said which I think are totally wrong. For one, if the U.S. were the only one to pull out, we'd look pretty stupid, frankly," Roosevelt said.

"As I've said many times, we've not going to change Soviet policy, nor embarrass them, by not showing up, sitting on a pile of sour grapes like a bunch of old ladies wringing their hands," Roosevelt continued.

Roosevelt indicated that he would vote against withdrawing the American team when the matter comes before the USOC executive board, of which he is also a member.

He said that he was certain the IOC would not move the games from Moscow, but that he might vote in favor of that when the IOC meets at Lake Placid on Feb. 10 through 12, just before President Carter opens the Winter Games there on Feb. 13.

Roby, also a member of the USOC executive board, said he would vote in that forum, to support the president's request, and thought most other members would as well.Roosevelt seemed to be in a distinct minority in his intention to vote to send an American team to Moscow against the Carter administration wishes.

Roby said he would probably vote against a proposal to move the games from Moscow in the IOC meetings at Lake Placid, though, because he considers such a move "infeasible."

The USOC has agreed to present the case for moving or postponing the games to the IOC, but officials privately say that it is a futile effort to sway an intransigent organization.

Kane said he was "very pleased" with Carter's statement yesterday because it was firm, but still gave the USOC some time to maneuver -- at least until the Feb. 20 deadline the president set for the Soviets to withdraw, and possibly longer, since Olympic entries do not have to be filed until early July.

"I'd like for us to stay flexible in this because we hope very much that the games will go on and we can take part in them. Now we've got at least a month of flexibility, which we wouldn't have had if he had enacted a boycott," Kane said.

"Now, we have a chance to talk to other nations, to see whether possibly world tensions will be relaxed, to hope for a miracle; that the Soviets will move out of Afghanistan."

Kane was careful to draw a distinction between the president's request that U.S. athletes not participate in the Olympics if Soviet troops remain in Afghanistan and what he called "a boycott."

"A boycott would have taken us out of the Olympic movement altogether, leaving us without a voice in the deliberations and the decision-making," said Kane, who had feared that the administration would order Americans to shun the Moscow games without going through the USOC and following IOC procedures.

"We have a problem not with the Olympic Games, but with the site for 1980, and I think that ought to be pursued the way the president has now suggested. We can work within the framework of the IOC and its rules and not necessarily send our athletes to Moscow," Kane added.

Presidential counsel Lloyd Cutler, who will attend the USOC executive board meeting next weekend, said yesterday that "the U.S. government, if necessary and if it decided to do so, could prevent American athletes from participating," even if the USOC voted to send a team.

But Kane doubted that it would ever become necessary for the administration to enforce a ban against the USOC's and athletes' will, using control of passports or other means. He also said that it would be impossible for American athletes to enter the games as individuals if the USOC does not send a team to Moscow because "IOC rules do not permit it."

"Some of the African athletes wanted to do that in 1976," Kane said, recalling the boycott of the Montreal Summer Games by 29 Black African nations because Britain was not expelled for its rugby contracts with South Africa, "but they weren't permitted to compete because they weren't representing a country."

Fears that the Soviet Union would withdraw from Lake Placid if the president took a strong stand against the Moscow games were allayed by the article in Sovietsky Sport, which denied as "slanderous fabrication" any speculation that the Soviets would boycott the Winter Olympics.

The article followed statements Friday by USOC Director Miller, who had warned that "of the 38 countries entered in Lake Placid, 13 are in the Soviet orbit . . . They could retaliate against the Winter Games."

The Carter administration has said it will not deny visas to Soviet athletes.

Lord Killanin said that decisions not to send teams to Moscow "through political pressures" could have "the most detrimental effect on the long-term future of the Olympic movement, of world sport, and especially the games in Los Angeles." He predicted that if the United States and its allies boycotted Moscow, nations with opposing ideologies would likewise boycott Los Angeles.

Peter Uberroth, chairman of the organizing committee for the 1984 games in Los Angeles, acknowledged that this was possible, but said; "This is a world crisis, not a matter of politics. Very clearly, any American citizen in a time of crisis should back our president."

Of all the private American companies with a financial stake in the Moscow Games, none has a greater involvement than NBC, which is insured for 90 percent of its initial $87 million investment by Lloyd's of London, but has no way of recovering the estimated $20 million it has already spent on production costs or the "rating boost" it expected 150 hours of Olympic programming to provide.

"NBC feels much the same way as the athletes do. We see four years of hard training going down the drain," said an NBC executive. "But if Americans don't participate, we won't televise the games."