Nobuhiko Okabe, who heads the Kawasaki City Institute for Public Health, spoke to Kyodo News and said the Games would cause an increase in infection.

"The Olympics present one of the most difficult situations when it comes to infectious disease prevention," said Okabe.

"It's a cluster of risks, with people gathering from all over the world.

"As long as the Games are held, we have to make people understand that the number of infections will likely increase.

"Stopping the Games is an unlikely option the way things are now, but supposing the number of infections surges and hospitals become overburdened, we would need to be able to make the brave decision to call them off.

"It needs to be clear who would decide that.

"In the situation we're in, I wouldn't say 'stop worrying, it's OK to hold the Games', but at the current level I think it can be done with care.

"We (health experts) are the ones who need to show how and where to take precautions."

Due to the ongoing COVID-19 pandemic, the Olympics have been postponed to 2021 and are currently scheduled to take place from July 23 to August 8.

They are scheduled to be followed by the Paralympics from August 24 to September 5.   

Despite Tokyo 2020 officials and the International Olympic Committee stating that the Games will take place, the virus has seen a resurgence in recent months.

Okabe serves as an advisor to a panel jointly formed by the Japanese Government, the Tokyo Metropolitan Government and the Tokyo 2020 Organising Committee.

He said that while the best way to avoid an outbreak is to not hold the Games, he said "there's no sense now in debating endlessly".

"Instead the debate should be what needs to be done in order to keep infections contained to a small scale, but infections cannot be reduced to zero," said Okabe.

"That's the information we experts have to convey."

Okabe also believes that information on the virus is becoming clearer and there should be further progress in six months.

"It's better if infections don't spread, but the more important thing is not to add to the count for serious cases," he added.

"And the collapse of the country's health care system, at any place, must be avoided at all costs."

Last month, the panel that Okabe is a part of announced that Japan would allow foreign athletes to enter the country for the Games if they meet requirements such as testing negative for the virus and avoiding public transport.

Around 11,000 athletes from more than 200 countries and territories were expected to participate at Tokyo 2020 prior to the pandemic, but it is unknown yet whether numbers will be affected.

Okabe has previously served as the regional advisor for the World Health Organization Western Pacific Regional Office in Manila in The Philippines.

He was also the director of the Infectious Disease Surveillance Center at Japan's National Institute of Infectious Diseases.