TOKYO: Athletes must wear masks at all Tokyo Olympic Games venues, including medal ceremonies, the International Olympic Committee said on Sunday, but under a new policy they are briefly allowed to remove them on the podium for a photo opportunity.

Masks are mandatory across all venues, both inside and outside, for all athletes, staff and media, as part of Games organisers' strict measures to combat the coronavirus.

"It's not a nice to have. It's a must to have," said IOC spokesman Mark Adams.

"No, there is no relaxation and we would urge and ask everyone to obey the rules," Adams said. "It's important for the sports, for everyone involved and for our Japanese friends and it would send a strong message."

But athletes can briefly take them off on the podium for 30 seconds for a photo opportunity, the IOC said,

During Sunday morning's swimming finals, American Chase Kalisz took off his mask on the winners' podium after his gold medal performance in the men's 400 metres medley.

He was standing next to mask-less compatriot and silver medallist Jay Literland and Australian Brendon Smith, who took the bronze and also removed his mask.

"The swimmers in the venue this morning followed instructions which they were given by the protocol team," an IOC spokesperson said.

"These instructions were in line with a new policy which in the process of being communicated to all."

"It allows for a socially distanced photo opportunity for a maximum of 30 seconds on the podium."

Team Australia also confirmed their athletes had done nothing wrong.

"Our athletes were simply following the direction of the official at the podium, who holds up a sign saying masks off briefly for the photographs," a Team Australia official said.

The Tokyo Olympics are held mostly without spectators as the capital has seen a rise in daily COVID-19 cases in recent weeks.

All 12 athletes from Australia, Canada and the United States on the podium for the women's 4X100 freestyle relay ceremony were mask-less, smiling to photographers.

The Olympic teams of Kyrgyzstan and Tajikistan had paraded mostly maskless through the National Stadium at Friday's opening ceremony, making an awkward contrast with other national teams who covered their faces in line with COVID-19 protocols.

Organisers announced another 10 positive COVID-19 cases to Games-related individuals on Sunday, bringing the total to 132 cases since July 1.