The head of the Japanese government's coronavirus advisory panel has suggested that Japan has entered a seventh wave of coronavirus infections.

Omi Shigeru and other infectious disease experts met Prime Minister Kishida Fumio on Monday.

Speaking to reporters after the meeting, Omi said they explained to Kishida that the surge in case numbers now underway could be attributed in part to the spread of the Omicron subvariant BA.5, which is believed to be more transmissible than earlier strains.

They also pointed to other factors including the weakening of immunity provided by vaccinations arising from the long period of time since most people's last shot.

Omi said the experts asked Kishida to ensure that the central and local governments put preparations in place to offer the medical care, testing and vaccinations likely to be necessary.

They also requested that the government call on people to follow basic anti-virus measures.

Omi told reporters that while he believes Japan is now experiencing a new wave of infections, he is not calling for the introduction of restrictions, such as quasi-emergency measures, at the moment.

He suggested that it would be possible to overcome the current surge through testing, vaccinations and thorough implementation of basic preventative measures.