Tokyo 2020 Coordination Commission chair John Coates has acknowledged the growing petition against hosting the Olympic and Paralympic Games is "a concern" but stressed the event will take place.
An online petition has now received nearly 275,000 signatures since it was launched earlier this week, calling on organisers to "cancel the Tokyo Olympics to protect our lives" amid the COVID-19 pandemic.
The petition has been addressed to International Olympic Committee (IOC) President Thomas Bach and International Paralympic Committee President Andrew Parsons.
Japan’s Prime Minister Yoshihide Suga, Tokyo Governor Yuriko Koike, Tokyo 2020 President Seiko Hashimoto and Olympics Minister Tamayo Marukawa are also addressed in the petition.
The petition was launched by Kenji Utsunomiya, who lost to Koike in the Tokyo Governor election last year.
Utsunomiya had called for the cancellation of the Games as part of his campaign.
Coates, an IOC vice-president and head of the organisation's Coordination Commission for Tokyo 2020, told reporters in Australia that the Games "absolutely is going ahead".
He suggested that the number of signatures correlated with the slow vaccine rollout in Japan to date, with only around two per cent of Japan's population so far vaccinated against COVID-19.
"That is a concern," Coates said, according to Reuters.
"I think that there's a correlation between the numbers who are concerned about their safety with the numbers who have been vaccinated in Japan.
"And the numbers are very small, particularly amongst the elderly.
"And so as the vaccine is rolled out in Japan, I think that will improve.
"These measures we've been taking and trialling at the test events are working,
"The athletes at the test events are in a similar Olympic bubble to that they will be at the Games."
The Japanese Government yesterday extended and expanded a COVID-19 state of emergency, with measures in place in Tokyo and other prefectures until at least the end of May.
Among the emergency measures, restaurants and bars will be prohibited from serving alcohol or offering karaoke services and must close by 8pm.
Department stores and cinemas will be allowed to reopen from Wednesday (May 12), but must also close by 8pm.
Spectators are set to be permitted at sporting events in the six prefectures under restrictions, but there will be a cap of 5,000 people or 50 per cent of the venue's capacity.
A decision on spectator limits at the Games will not be taken until June, although organisers admit the Olympic and Paralympic Games may be held behind closed doors.
The IOC and Tokyo 2020 published updated version of their "playbooks", which outline the strict rules participants must adhere to at the Games, last week.
Athletes and all those with close proximity to competitors will be tested daily and everyone at the Games will be required to take two COVID-19 tests within 96 hours before they fly to Japan.
Visits to restaurants and bars have been banned, while athletes have been told to arrive no earlier than five days before their event and depart no later than two days after to limit the number of people at the Athletes' Village.
The IOC has warned those who breach the rules could be stripped of their accreditation, and the regulations will be in place irrespective of whether participants have been vaccinated or not.
The IOC was boosted this week by an agreement for the Pfizer COVID-19 vaccine to be donated to athletes heading to the Games, with a similar deal already in place with China and Russia offering vaccines to African National Olympic Committees.
The Tokyo 2020 Olympics are scheduled to take place from July 23 to August 8.