Olympic chief Thomas Bach said Monday he is “very, very confident” that spectators will be able to attend next year's Tokyo Olympics, as he kicked off a Japan trip to boost momentum for the pandemic-postponed Games.

Bach pledged the International Olympic Committee would work to ensure as many participants at next year's Games as possible were vaccinated, if a vaccine is available, but added that would not be a requirement for the event.

Spiralling infections and new lockdowns around the world have caused renewed scepticism that the massive international event will be possible if the pandemic is not under control by the time of the opening ceremony, now scheduled for July 23, 2021.

But organisers and Japanese officials have insisted they can hold the event, and are drawing up a raft of coronavirus countermeasures intended to make the Games safe even if the pandemic is not over.

“We are putting really a huge tool box together in which we will put all the different measures we can imagine,” Bach said, after meeting Japanese Prime Minister Yoshihide Suga for talks that began with the two masked men fist-bumping for the cameras.

“This makes us all very, very confident that we can have spectators in the Olympic stadia next year,” added Bach.

The Olympic chief said the IOC would “undertake great efforts” to make sure as many participants and spectators as possible were vaccinated before arriving in Japan.

But at a press conference, he clarified that “we never said that we can make it obligatory or a requirement”.

“We want to convince as many foreign participants as possible to accept a vaccine,” he said, adding “the IOC would take these costs,” without giving further details.

Bach, on his first trip to Tokyo since the Games were postponed in March, is hoping to persuade athletes, Japanese citizens and Olympics sponsors that the Games can be held safely next year.

Polls show a majority of Japan's public believe the Games should be postponed further, or cancelled altogether.

And more than 60 percent of domestic sponsors have yet to commit to extending their contracts for another year, domestic media reported this weekend.

But there are glimmers of hope for organisers and Japanese officials, who have insisted a further delay is not on the table, and that cancellation is not being discussed.

News last week of positive results in a late-stage vaccine trial were welcomed by Tokyo 2020 officials as a “relief”, though organisers cautioned that they will continue to prepare measures to hold the Games even without a vaccine.