People pose next to the Olympic Rings in front of the Japan Olympic Museum in Shinjuku, Tokyo. Photo: VCG

The development of a coronavirus vaccine or treatment will be key to allowing the postponed Tokyo 2020 games to open in a year's time, organizing committee president Yoshiro Mori said Wednesday.

Asked what factors will be crucial for the rescheduled Games to go ahead, Mori said "it would be whether the coronavirus woe is settling down."

"Specifically, the first point will be that a vaccine or drug has been developed," he said in an interview with national broadcaster NHK, published Wednesday.

Asked whether Tokyo could hold the Games if the virus situation remained unchanged, Mori said, "If things continue as they are now, we couldn't."

But he said that scenario was hypothetical. "I can't imagine a situation like this will continue for another year." 

Tokyo 2020 should have been opening on Friday, but the Games was postponed in March as the coronavirus spread across the globe, marking the worst disruption to an Olympics since two editions were cancelled during World War II.

The Games is now set to open on July 23, 2021, but recent polls have shown less public enthusiasm for hosting the event, as virus cases show a resurgence in Japan.

Just one in four people in Japan want to see the delayed Tokyo Games held next year, with most backing either further delay or a cancellation, according to a survey published by Kyodo News this week.

Most of those backing a delay or cancellation said they simply didn't believe the pandemic could be contained in time for the Games.

Among the options that have been floated for a Games held during a pandemic is the possibility of limited spectators, or holding the event behind closed doors.

But Mori said reducing the number of spectators would be tough. And he said holding the event without any fans was not an option for now.

"If it's the only way to do it, then it's something we'd have to consider. If that happens, there might be talk of cancellation," he was quoted as saying, without elaborating.

With just over a year to go until the rescheduled Games, there are persistent doubts about whether the delay will be sufficient for the pandemic to be brought under control.

Japan has so far reported 26,300 COVID-19 cases with 989 deaths, but Tokyo has seen an increase in cases recently and the country's borders remain almost completely sealed to overseas visitors.