Wearing masks when outdoors is not always necessary even if sufficient social distancing cannot be maintained, with the caveat that people are not conversing, a Japanese government panel of experts on COVID-19 measures said Thursday.

Based on the panel's view, the government of Prime Minister Fumio Kishida will announce its policy Friday, an official said.

The panel, headed by Japan's top coronavirus adviser Shigeru Omi, also expressed the view that elementary school students do not need to wear masks when outdoors during physical education classes or recess as long as distancing is maintained.

People wearing face masks walk in Osaka's Minami area on May 19, 2022. (Kyodo)

It marks the first time the health ministry's panel has clarified its stance on the necessity of wearing masks outdoors. Public debate is arising on how much longer people need to wear face-coverings to combat the coronavirus, as mask requirements have been easing overseas in line with progress in vaccinations against COVID-19.

Chief Cabinet Secretary Hirokazu Matsuno said last week that wearing masks outdoors to protect against the coronavirus is not necessary providing social distancing is practiced, with the approach of summer increasing the risk of heatstroke.

The panel at its meeting Thursday said people should still continue to wear masks on crowded public transport, and that they should bring a mask to wear when it gets crowded outside or during conversations.

The panel recommended in February that preschool children aged 2 and over wear masks amid the spread of the Omicron variant of the virus. But Omi said concerns had been raised that they might suffer from heat-related conditions or become stunted in development due to difficulties in reading facial expressions.

"It's time to consider returning to" not uniformly requiring the wearing of masks, Omi said.