International Olympic Committee officials have hit back at claims the Tokyo Games have put significant added pressure on Japan's coronavirus-hit medical system.

Host city Tokyo had 3,865 new cases on Thursday, up from 3,177 on Wednesday, as it set a record high for a third straight day.

The surge in COVID-19 cases has added to concerns about the decision to stage the Games and its impact upon on Japan's health infrastructure.

Tokyo 2020 is taking place under unprecedented conditions, with fans unable to attend while athletes are subjected to strict testing to identify and isolate positive cases.

And IOC medical and scientific director Richard Budgett insisted these regulations inside the Olympic bubble had negated any significant impact.

"This is the most tested community anywhere in the world. The athletes in the Olympic Village really are living in a parallel world," Budgett said.

"As far as I’m aware, there has not been a single instance of an athlete case spreading to the local population, and not a single severe case has occurred among our stakeholders.

"There are two positive cases who are in hospital, but no severe cases at this stage. 

"It is challenging for any country when there are rising cases, but I am confident the Olympics are being run without affecting that secondary care in hospital provision."

Kirsty Coventry, chair of the IOC athletes' commission, has responded to complaints from Dutch skateboarder Candy Jacobs that conditions at quarantine hotels are "inhuman".

Jacobs tested positive for COVID-19 and posted on Instagram about initially not being permitted to get fresh air during isolation because her hotel window did not open.

Coventry said: "We have been working very closely with TOCOG [the Tokyo Organising Committee of the Olympic and Paralympic Games] about improving all those experiences [at] the quarantine centres and hotels.

"Candy and others have raised similar points. We have reached out to them and are working with them to make sure conditions are improved."