Samoa has become the second country to withdraw some athletes from the Tokyo Olympics as fears grow of a depleted Games being staged under a renewed state of emergency.

Meanwhile, visiting officials and media have been handed a Big Brother-style warning that that they risk being watched and shamed on social media if they fail to adhere to stringent quarantine conditions.

The Samoan Olympic Committee confirmed it has withdrawn three weightlifters who had qualified for Tokyo, but said eight other team members, none of whom are based on the Pacific island, will still attend the Games.

A statement said the decision over the weightlifters, who are all based in Samoa, was taken reluctantly in order to "protect our borders", citing the continued struggle to contain the virus on nearby Fiji.

So far, North Korea is the only other nation to have voluntarily withdrawn athletes, having announced in April that it would not be sending any athletes to the Games due to risks associated with the virus.

Meanwhile the continuing rise in coronavirus cases in Japan has prompted a member of the government's ruling coalition to suggest the Games could take place without fans after all.

The government announced last month that venues can be filled to 50 per cent capacity, provided the current 'quasi-state of emergency' affecting Tokyo and surrounding prefectures is lifted on July 11.

However, a sharp rise in cases, with 714 reported in Tokyo in the latest figures released on Wednesday, have led some to predict tougher measures, including a fan-ban, could be re-imposed.

Natsuo Yamaguchi, leader of the Komeito party, told reporters in Japan: "I've said we need to be on the lookout for a rebound in infections, and that's exactly what we are seeing now.

"I hope the government will remain open to the possibility of there being no spectators and inform the public of any decisions in a timely manner."

Athletes and other Games visitors will be subject to strict quarantine procedures in Tokyo, with most facing the prospect of being effectively sealed off from the Japanese public during their first fortnight in the city.

The consequences of breaking rules, which are intended to off-set local fears of the impact of foreign visitors on the coronavirus statistics, were made plain in a missive to stakeholders on Tuesday.

It warned: "The people of Japan will be paying close attention to your every move as you participate in the Games.

"In the unlikely event that your are suspected or found to be in infringement of the Playbook, such activity may be photographed and shared on social media by bystanders."