Published: 2021-07-25 11:20:41 BdST
Masks are mandatory across all Olympic venues, both inside and outside for all athletes, staff and media, as part of Games organisers' strict measures to combat the virus.
"It's not a nice to have. It's a must to have," said IOC spokesman Mark Adams, responding to questions about the mask-less swimmers.
American Chase Kalisz took off his mask on the winners' podium after his gold medal performance in the men's 400 metres medley, hugging compatriot and silver medallist Jay Literland, who was also mask-less. Australian Brendon Smith, who took the bronze, also removed his mask.
A little later all 12 athletes from Australia, Canada and the United States on the podium for the women's 4X100 freestyle relay ceremony were mask-less, hugging teammates and smiling to photographers.
"No, there is no relaxation and we would urge and ask everyone to obey the rules," the IOC's Adams said. "It's important for the sports, for everyone involved and for our Japanese friends and it would send a strong message."
"We understand ... there's a lot of excitement and of course when you win a medal, we feel for the athletes," Adams said.
"There are things that unfortunately we have had to make stricter. It is really in our own interest, in the interest of everyone and in the interest of safe and secure Games that we obey these rules."
The Olympic teams of Kyrgyzstan and Tajikistan had paraded mostly maskless through the National Stadium at Friday's opening ceremony, marking 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.
The Tokyo Olympics are held mostly without spectators as the capital has seen a rise in daily cases in recent weeks, reaching 1,979 on Thursday, the highest since January.