The "bubble" to control Covid-19 infections at the Olympic athletes' village in Tokyo is "broken" and could pose a risk to the general public, a prominent public health expert has said a few days ahead of the opening of the Tokyo 2020 Olympic Games. 

"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.

The Associated Press news agency reported on Tuesday that a total of 71 people had tested positive among those accredited for the Games since July 1, including at least six athletes, Games contractors and volunteers. 

The first infections among athletes were reported on Sunday, sparking concerns that some games may be subject to delays. In total, 11,000 athletes are expected to stay at the Olympics village in Tokyo. 

Risk of spreading infections

"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," Shibuya, who had previously argued the Olympics must be "reconsidered" due to Japan's inability to contain coronavirus cases, said.

Two members of Mexico's Olympic baseball team were the latest to have tested positive for Covid-19 at the team hotel before their departure for the Tokyo Olympics and were in isolation.

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, Shibuya 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".

Football match with South African team to go ahead 

A Japan Olympics Committee official told Reuters on Tuesday that a match with the South African football team, scheduled for Thursday against Japan, could still take place with "proper measures". 

Two players and a team video analyst had tested positive on Sunday, and were moved to the “isolation facility” managed by the Olympic organising committee. 

Some 21 close contacts in the team are under "extra scrutiny". 

The official said infections at the village were likely to be from before athletes left their countries. 

READ MORE:Four Olympics athletes test positive ahead of Tokyo 2020 opening

Cases in Tokyo at six-month high

New Covid-19 cases in Tokyo reached 1,410 on Saturday, a near six month high.

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 percent 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. 

READ MORE:Tokyo Olympics: Fans banned from Games venues amid Covid emergency