The head of the organising committee for the Tokyo Olympics has not ruled out a last-minute cancellation of the global sporting showpiece, amid rising coronavirus cases that have presented organisers with mounting challenges.

Asked if the Games, which are due to open on Friday, might still be cancelled, Toshiro Muto said he would keep an eye on infection numbers and hold discussions with organisers if necessary.

“We can’t predict what will happen with the number of coronavirus cases. So we will continue discussions if there is a spike in cases,” Mr Muto said.

“We have agreed that based on the coronavirus situation, we will convene five-party talks again.

“At this point, the coronavirus cases may rise or fall, so we will think about what we should do when the situation arises.”

COVID-19 cases are rising in Tokyo rising and the Games, postponed in 2020 because of the pandemic, will be held without spectators.

Earlier in July, Japan decided that participants would compete in empty venues to minimise the risk of further infections.

The opening ceremony will also take place without major Olympic sponsors, the companies said on Tuesday, dealing another blow to a slimmed-down Games as more athletes tested positive for the coronavirus.

Mr Muto, a former top financial bureaucrat with close ties to Japan’s ruling party, is known for his careful choice of words. But organisers are facing a domestic public angry about COVID restrictions and concerned about a possible spike in cases triggered by Games.

Public concern has grown that hosting an event with tens of thousands of overseas athletes, officials and journalists could accelerate infection rates in Japan’s capital and introduce COVID-19 variants that are more infectious or deadlier.

Officials from top Olympic sponsor Panasonic Corporation, as well as Fujitsu Ltd and NEC will skip the event, several local media outlets have reported. On Monday, Toyota dropped all TV ads linked to the Games.

Organisers, for whom International Olympic Committee president Thomas Bach said cancelling the event had never been an option, have promised to keep the Games “safe and secure”.

But experts see gaps in an Olympic “bubble” that mandates frequent testing and has been designed to limit participants’ movements.

There have been 67 cases of COVID-19 infections in Japan among those accredited for the Games since July 1, when many athletes and officials started arriving, organisers said on Tuesday. That does not include those at local training camps.

Two members of Mexico’s Olympic baseball team tested positive for COVID-19 at the team hotel before their departure for Tokyo, the country’s baseball federation said.

The athletes, Hector Velazquez and Sammy Solis, who tested positive on July 18, have been isolated, as have all team members pending results of more tests.

The first major test of how an Olympics can be held in the midst of a pandemic may well come on Thursday. In the men’s soccer tournament, Japan faces a South Africa side that could struggle to field 11 players due to the coronavirus.

Mr Bach said on Tuesday organisers could never have imagined the “unprecedented challenges” of bringing the global event to Tokyo, and praised the “heroic efforts” of medical personnel and volunteers around the world amid the pandemic.

“The IOC never abandons the athletes. Therefore, we took an unprecedented decision to postpone the Games. Today I can admit we did not know how complex this would be,” he said.

Comments by Mr Bach and other IOC officials in the run-up to the Games have sparked outrage on social media in Japan for appearing to dismiss concerns about the pandemic.

“It’s obvious that the bubble system is kind of broken,” Kenji Shibuya, the former director of the Institute for Population Health at King’s College London, said this week.

“My biggest concern is, of course, there will be a cluster of infections in the [athletes’] village or some of the accommodation and interaction with local people.”

Japan has recorded more than 840,000 cases of COVID-19 and 15,055 deaths. Host city Tokyo is experiencing a fresh surge, with 1387 cases recorded on Tuesday.

-AAP