International Olympic Committee member Dick Pound believes the IOC has already decided to postpone the Tokyo Olympics because of the coronavirus pandemic.
The IOC has given itself four weeks to decide on the future of this year's Games, which are due to start on July 24.
But in a newspaper report Mr Pound said the Games were likely now to be held in 2021, with the details to be worked out in the next four weeks.
"On the basis of the information the IOC has, postponement has been decided," Mr Pound told USA Today on Monday.
"The parameters going forward have not been determined, but the Games are not going to start on July 24, that much I know."
Australia and Canada withdrew from the Games on Monday as organisers faced global pressure to postpone the Olympics for the first time in their 124-year modern history.
Great Britain are unlikely to send a team to Tokyo should the Games go ahead, British Olympic Association (BOA) chairman Hugh Robertson said on Monday.
The Swiss Olympic Committee also called for a postponement, saying a fair, global Games was not currently possible while Iran later on Monday added its voice via a letter from the head of National Olympic
Committee, Reza Salehi Amiri, to IOC President Thomas Bach.
And Mr Pound, the 77-year-old Canadian and former IOC vice president said he believed the IOC would announce its next steps soon, adding: "It will come in stages.
"We will postpone this and begin to deal with all the ramifications of moving this, which are immense."
Mr Pound also told Reuters that the IOC had tried to hold fire in order to be able to present the hosts, sports federations and sponsors with a clear alternative plan.
"Probably what turned the tide in the last couple of days is the curve on the COVID-19 virus. It is getting very, very steep now and this is clearly not something that is going to be under control by June or July and probably not by the end of the year."
Japanese Prime Minister Shinzo Abe said he now does not believe the Tokyo Games can be held under current circumstances.
"If I'm asked whether the Olympics can be held at this moment, I would have to say the world is not in such a condition," Mr Abe told a parliamentary session on Monday.
German Olympic Sports Federation (DOSB) president Alfons Hoermann welcomed the IOC's move but said "we would have wished now for a clear statement that the Games definitely cannot take place on the planned dates and now advise is being taken on alternatives."