The U.S. Olympic Committee has renewed its efforts to rally international support for a one-year postponement of this summer's Olympic Games in Moscow as a means of heading off a widespread boycott that could rupture the Olympic movement.

Col. F. Don Miller, executive director of USOC, said yesterday that "we are making a very strong thrust for postponement," based on the prospect that as many as 50 nations are likely to boycott the Moscow Games because of the Soviet Union's military presence in Afghanistan.

The French Olympic Committee voted yesterday to send a team to Moscow -- a disappointing blow to the Carter administration, which had appealed for unity among Western European allies against participation in the Games.

Secretary of State Edmund Muskie, who Monday made a personal appeal to French Foreign Minister Jean Francois-Ponet for France to join the Olympic boycott, expressed disappointment at the news from Paris.

"I know that in France the word detente is a popular word," Muskie said on his arrival in Brussels yesterday, "but detente will not work unless there is deterrence. The two words go together."

However, the success of a boycott, and of the new attempts to have the Games postponed, is expected to hinge more on the decision of the West German Olympic Committee, which will meet Thursday.

The International Olympic Committee, which owns the Olympics and oversees their conduct, has heretofore resisted all calls for the Games to be moved from Moscow, canceled or postponed in repudiation of Soviet agression in Afghanistan.

Miller said he still thinks there is a "realistic possibility" of gaining the two-thirds vote of the 88 IOC members necessary for postponements, expecially if such important nations as West Germany, Japan and Australia join the boycott before May 24 deadline for Olympic entries.

So far, the national Olympic committees of 29 countries -- including the United States, Canada and China -- have decided not to send teams to Moscow this summer.

Miller said he expects the number of boycotting nations to increase to "between 45 and 50" over the next 10 days, as undecided Olympic committees meet.

If the West Germans decide to boycott, as their government has urged, a number of other Western European Olympic committees are expected to follow suit.

"I think the West German decision will have a major impact on Italy (whose Olympic committee also meets Thursday), Belgium, Holland and most of the Scandinavian countries," said Miller, who has maintained close contact with his counterparts in Europe.

Miller spoke by telephone yesterday with Willi Daume, president of the West German Olympic Committee, influential member of the IOC and the leading European supporter of postponement of the Moscow Games.

"He said he was not able to project how the German committee would vote. He could not indicate which direction it would take," Miller said, reinforcing the widely held impression that the German meeting will be heated and sharply divided.

Daume proposed to a May 3 meeting of 18 Western European Olympic committees in Rome that the IOC be petitioned again to postpone the Games. That proposal was tabled in favor of a British proposal that European nations go to Moscow, but support an eight-point plan to deemphasize nationalism at the Games.

Daume and Miller both think that a one-year postponement is the best available solution to the current Olympic crisis, however, and are pressing for the IOC to reconsider it at its Executive Board meeting in Lausanne, Switzerland, June 9.

A postponement would buy time for a possible Soviet troop reduction in Afghanistan that might enable countries now inclined to boycott to reconsider their positions and participate in the Moscow Games, proponents argue. This could head off a schism within the 148-nation Olympic family that could have grave repercussions for the future of the Games, they say.

"I think there is still a possibility of getting a two-thirds vote for postponement in the IOC, if the members can be convinced that this might permit the Games to go on in 1981 without a large number of countries boycotting," Miller said in an interview with The Washington Post.

"When you look at the number of countries that may not participate in the Games, and consider their interest in preserving the Olympic movement, I think most of them would be for it."

Miller said he discussed postponement at length with IOC President Lord Killanin following a meeting of the IOC Executive Board in Lausanne last month. Killanin was "lukewarm" on the proposal and skeptical about getting the necessary two-thirds vote, but agreed to keep the option open, Miller said.

Miller and USOC President Robert J. Kane discussed the postponement plan with many of the 27 national Olympic committees represented at a meeting of the Pan American Sports Organization last week in Guatemala City. "Most of them were in favor of it," Miller said.

Miller met with White House officials in Washington Thursday and Friday, and said they favored seeking a postponement. It was the Carter administration's request that the USOC appealed to the IOC in February to move, cancel or postpone the Moscow Games, a proposal that was unanimously turned down.

Miller said he thinks most of the athletes who would have competed in Moscow this summer would continue training if they think there is a chance of competing in 1981.

The Moscow Olympic Organizing Committee has not indicated whether it would accept a postponement, Miller said. Lord Killanin is believed to have raised this possibility during his meetings with Soviet President Leonid Brezhnev and Soviet Olympic officials in Moscow last week.

Meanwhile, there was the French Olympic Committee's decision yesterday.

Claude Collard, president of the French committee, said the decision of the executive committee, after consultation with the governing federations of 23 sports, was nearly unanimous -- 22 votes for sending a team and one abstention.

The French government said in January that it would not intervene in the decision of the Olympic committee, but Sports Minister Jean-Pierre Soisson said subsequently it was unlikely that France would participate in Moscow if it were the only major Western nation to do so.

French government officials indicated yesterday that they would wait for West Germany's decision Thursday and a meeting between Muskie and Francois-Ponent Friday before responding to the committee's decision.

In related developments, the Sports Committee of the Israeli Knesset (parliament) recommended that Israeli athletes not participate in Moscow, and Zimbabwe -- the former British colony of Rhodesia which was officially admitted to the IOC yesterday -- said it would send a team.

The nations whose Olympic committees already have decided against sending teams to Moscow are Albania, Argentina, Bermuda, Bolivia, Central Africa, Canada, Chad, Chile, China, Egypt, Gambia, Haiti, Virgin Islands, Kenya, Liberia, Liechtenstein, Mali, Papua-New Guinea, Norway, Pakistan, Paraguay, Saudi Arabia, Singapore, Somali, Sudan, Taiwan, Uganda, United States and Zaire.