Here, the PA news agency looks at the main questions surrounding the Games.

What is the current state of play?

The Games remain scheduled to begin on July 24. But there are increasing calls to delay or cancel the event. For weeks, Japanese officials have said the Games will go ahead but prime minister Shinzo Abe has now admitted for the first time a postponement is a possibility if the event cannot take place in full, although he insisted it would not be cancelled entirely.

The International Olympic Committee is in discussions with the Tokyo 2020 Organising Committee and expects a decision within four weeks. Meanwhile, the Olympic flame has reached Japanese soil.

However, Canada’s decision not to send any athletes to Tokyo unless the Games are postponed by at least a year is a huge statement. Australian competitors have been told to expect an inevitable delay. US Track and Field has called for a postponement, as have a number of athletes, while isolation rules have left many competitors unable to train.

What are the officials saying?

Mr Abe said the postponement of the Games would be unavoidable if it cannot be held in a “complete way”. The IOC is discussing “scenarios (which) relate to modifying existing operational plans for the Games to go ahead on July 24, 2020, and also for changes to the start date of the Games”.

World Athletics president Lord Sebastian Coe said a decision “may become very obvious very quickly in the coming days and weeks”, and UK Athletics chairman Nic Coward believes “stress” caused by the pandemic will lead to the Games being postponed.

Team Canada has “made the difficult decision to not send Canadian teams to the Olympic and Paralympic Games in the summer of 2020” and called for it to be postponed for a year, while Australian Olympic Committee chief Matt Carroll said: “With travel and other restrictions this becomes an untenable situation.”

And the athletes?

Britain’s heptathlon world champion Katerina Johnson-Thompson has said the situation has left her “under pressure to train and keep the same routine, which is impossible”.

World 200m champion Dina-Asher Smith questioned the IOC leaving athletes trying to find ways to train for another four weeks, “whilst potentially putting ourselves, coaches, support staff and loved ones at risk just to find out they were going to be postponed anyway”.

Guy Learmonth, who hopes to compete in the 800m, said: “I’d be happy if they postponed until at least October, or maybe later to 2021 or 2022. At least that would give the athletes time to now plan, train, and more importantly, time for this virus to settle down.”

British cyclist Callum Skinner, who sits on the British Olympic Association’s Athletes Commission, blasted IOC President Thomas Bach’s “stubbornness and arrogance”.

Canadian tennis player Gabriela Dabrowski said competing in the Olympics was her number one goal but added: “I fully support this decision and I commend our leadership for taking a stand. I hope more nations follow suit.”

So when will a decision be made?

The IOC says it will decide within four weeks but if more countries follow Canada’s lead and pull their athletes out and the clamour grows for the Games to be delayed, that will surely change. Australia joined a number of countries, including Norway, Brazil and Slovenia to press the IOC on a possible postponement. Lord Coe expects a decision in the coming days and weeks but, until then, athletes across the world remain in limbo.