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."
There have been more 3 documented coronavirus cases globally, with more than 210,000 deaths, and the World Health Organization (WHO) warned on Monday that the pandemic was "far from over".
Earlier on Tuesday, the head of the Japan Medical Association said it will be difficult for Tokyo to host the Olympic Games next year unless there is an effective vaccine against the coronavirus.
"I am not saying that Japan should or shouldn't host the Olympics, but that it would be difficult to do so," JMA president Yoshitake Yokokura said in a media briefing.
The one-year delay of the 2020 Olympic Games announced last month was a major blow to Japan, which had already spent $13 billion preparing for the event. As the outbreak has spread around the world, infecting almost three million people and killing more than 200,000, experts have warned that the fight against the virus could be prolonged.