Team GB athletes may have to hard quarantine for six days on arrival at Tokyo 2020 Olympics.
The rising cases of the Delta variant in Britain means Team GB's athletes would have to quarantine as it stands, with the UK currently on Japan's red list.
Tokyo 2020 spokesperson Masa Takaya said: "Quarantine for six days is required for some countries where the same treatment will be imposed to athletes and media."
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Failure to comply with the rules could see athletes disqualified or even face deportation according to the latest guidelines published by the International Olympic Committee (IOC).
British Olympic Association (BOA) officials hope the restrictions will be eased following a review by the Japanese government set for July 1.
A BOA spokesperson said: "We continue to have positive dialogue with the IOC and the Tokyo Organising Committee, following our letter to the president of Tokyo 2020.
Our approach to additional testing measures and vaccinations for the delegation prior to departure and upon arrival demonstrate we are doing everything possible to minimise any risk to the people of Japan.
The IOC say they are supportive of nations who have taken extra steps, such as vaccinations for athletes, to ensure the Olympics remains disruption-free.
IOC executive director Christophe Dubi said: "Those countries that are affected by the variants have also made a pledge... whereby they will take extra measures on their side. They will ensure that a maximum number of their people are vaccinated.
"If there is a problem, of course we will follow the rule as established by the authorities, but we can do more, and this is what these delegations have pledged to do."
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