Government advisory panel chief Omi Shigeru said, "If the Olympics are to be held, we hope that the infection won't spread and medical care will not become strained. To that end, as an expert, I wrote in a proposal what the risks are and what kind of measures can be taken to deal with them."

Omi and other experts submitted their viewpoint to Tokyo Games organizers on Friday.

They warn new infection cases could increase in July and August even if the vaccine rollout continues smoothly across Japan.

They also note that more transmissible variants could speed up the spread of infection.

The experts add that the Games will create larger flows of people, which could result in another wave of infections, adding pressure on the healthcare system.

The proposal also recommends stricter restrictions than currently in place if domestic spectators are allowed into event venues.

The head of the organizing committee says the proposal will be a jumping off point for further talks.

Hashimoto Seiko said, "Based on Omi's proposal, I hope we can hold thorough discussions from an expert point of view on how to ensure the safety of the Games for everyone."

The final decision on domestic spectators is expected by the end of the month.

The experts' proposal comes as the government will end a state of emergency declaration on Sunday for nine prefectures, leaving only Okinawa's emergency in place.

But seven of the prefectures will still follow strict COVID measures for another three weeks.

If cases rise sharply, the government says it will act quickly.

That could mean once again urging bars and restaurants to stop serving alcohol, tightening restrictions on events, or declaring another emergency.