TOKYO: The so-called bubble to control COVID-19 infections at the Olympic Athlete's Village in Tokyo is already "broken" and poses a risk of spreading infections to the general populace, a prominent public health expert said on Tuesday.

Games officials on Sunday reported the first COVID-19 case among competitors in the athletes' village in Tokyo where 11,000 athletes are expected to stay. Since July 2, Tokyo 2020 organisers have reported 58 positive cases among athletes, officials and journalists.

"It's obvious that the bubble system is kind of broken," said Kenji Shibuya, the former director of the Institute for Population Health at King's College London.

"My biggest concern is, of course, there will be a cluster of infections in the village or some of the accommodation and interaction with local people."

Insufficient testing at the border and the impossibility of controlling people's movements mean that the Games could exacerbate the spread of the infectious Delta variant of the virus, he added.

International Olympic Committee President Thomas Bach said last week that testing and quarantine protocols would leave "zero" risk of Games participants infecting residents in Japan.

Declarations like that only serve to confuse and anger people, Shibuya said, as actual conditions on the ground are "totally opposite".

In April, Shibuya co-authored a commentary in the British Medical Journal that the Olympics must be "reconsidered" due to Japan's inability to contain coronavirus cases.

New COVID-19 cases in Tokyo reached 1,410 on Saturday, a near six month high, while the Games are due to start in just three days.

Public health experts have warned that seasonal factors, increased mobility, and the spread of the Delta variant could lead to a surge past 2,000 cases per day in Tokyo by next month, levels that could drive the city's medical system to breaking point.

Just 33% of people in Japan have received at least one COVID-19 vaccine dose, among the lowest rate among wealthy countries, according to a Reuters tracker. The vaccination push has gained steam since last month, but recently ebbed due to supply and logistical snags.

By contrast, Soma City in the northern prefecture of Fukushima where Shibuya headed its vaccination efforts recently completed the bulk of its inoculations, far ahead of most of Japan.