The chief executive of the Tokyo 2020 organising committee, Toshiro Muto, did not rule out a last-minute cancellation of the Olympics as more athletes tested positive for Covid-19 and sponsors ditched plans to attend Friday’s opening ceremony.

Muto said that organisers would continue to monitor the pandemic and declined to say that cancellation was not a possibility.

“We can’t predict what will happen with the number of coronavirus cases,” he said.

“So we will continue discussions if there is a spike in cases.”

He added: “At this point, the coronavirus cases may rise or fall, so we will think about what we should do when the situation arises.”

“We’re determined to realise safe and secure Games by thoroughly taking measures, with priority on protecting the health of citizens,” Japan’s prime minister, Yoshihide Suga said..

Tokyo city reported 1,387 new Covid-19 cases on Tuesday, an increase of 557 from last Tuesday.

There have been 67 cases of Covid-19 infections in Japan among those accredited for the Games since July 1, when many athletes and officials started arriving, organisers said on Tuesday.

Organisers have promised to keep the Games “safe and secure”.

But experts see gaps in an Olympic “bubble” that mandates frequent testing and has been designed to limit participants’ movements.