The issue was raised when IOC president Thomas Bach took questions to cap a two-day online conference hosted by the official Olympic commission representing athletes.

"I know this is a concern for a number of you," Bach said, before asking IOC chief operating officer Lana Haddad to give what he called "an expert's answer."

The waiver is included in the traditional entry form Olympic athletes must sign, which was "updated to include COVID-19 related consideration," Haddad said.

"This is really to provide transparency and ensure the informed consent from the games participants," she explained.

"The entry forms are consistent with the standard practice of all other big event organisers. And the forms are within the framework of the law, if I may add."

Athlete groups not formally recognised by the IOC have argued too much risk and responsibility is being placed on the 11,000 competitors set to take part in the July 23-August 8 Tokyo Olympics.

The games will bring tens of thousands more coaches, officials, media and other support workers into Japan.

The IOC and Japan's government insist the games will be safe and secure with participants kept mostly isolated from the general public.

Tokyo is currently in a state of emergency and fewer than five per cent of Japanese people have been vaccinated. The IOC claims at least 80 per cent of people staying in the Olympic village at Tokyo Bay would have been vaccinated.

"No government, no health authority can or has taken over guarantees against infections," Haddad told athletes. "This is a risk that we all bear. We are all following the same rules."

Olympic organisers have published so-called playbooks of health protocols all games attendees must follow and which are regularly updated.

The guide for athletes notes "despite all the care taken, risks and impacts may not be fully eliminated, and therefore you agree to attend the Olympic and Paralympic Games at your own risk."

Australian Associated Press