Tokyo 2020 president Yoshiro Mori said that the Olympic Games, already postponed to 2021, would be "scrapped" if it could not take place then, according to an interview published on Tuesday.
The International Olympic Committee and the Japanese government last month postponed the Games until July 2021 because of the impact of the coronavirus outbreak.
With the epidemic's worldwide infection rate climbing and experts suggesting a vaccine is still a long way off, questions are being asked about whether a further delay might be needed.
"No. In that case, the Olympics will be scrapped," Mori said in the interview with Japanese sports daily Nikkan Sports, when asked if the Games could be postponed again until 2022.
However the former prime minister remained confident the they would go ahead in 2021.
"We have delayed the Olympics until next summer after we will have won the battle," he was quoted as saying.
"The Olympics would be much more valuable than any Olympics in the past if we could go ahead with it after winning this battle. We have to believe this otherwise our hard work and efforts will not be rewarded."
Asked about Mori's comments, Tokyo 2020 spokesman Masa Takaya emphasised organisers were focusing on next year.
"New dates for the Tokyo 2020 Games have been set and our mission is to deliver the Games next year," he told a news briefing.
Mori "mentioned this comment in his own thoughts," Takaya added.
During the interview, Mori also suggested the Olympics and Paralympics might share opening and closing ceremonies instead of holding their usual separate ones.
Mori said this would cut costs, though the idea is further complicated by tickets already being sold for all four ceremonies.
"It's a big hurdle," he admitted. "(But) ... due to the impact of coronavirus, the situation next year will be completely different..., Given that the situation has dramatically changed, we have to review key areas, including the ceremonies."
Tokyo 2020 is set to run from 23 July to 8 August next year, but organisers expect few changes to the original plan, including attendance by enthusiastic supporters.
But that might be over optimistic, Zach Binney, an epidemiologist at Emory University in the United States, told Reuters.
"When we talk about bringing sports back with packed stadiums, I really think that is something we are going to have to wait for a vaccine to be able to do," he said.
The Olympics was "a uniquely risky event", he added, because of the threats represented by visitors streaming in from areas with a lot of infections, and the reverse flow when they return afterwards, perhaps carrying home infections.