* Foreign spectators already excluded from delayed Games
* Organisers to meet Thursday to discuss spectators
* Virus restrictions, public sentiment to affect decision
Japan is considering banning all spectators from the Olympic Games, several sources told Reuters on Wednesday, as officials weigh extending novel coronavirus restrictions to contain infections just over two weeks before the Games begin.
Medical experts have said for weeks that having no spectators at the Olympics would be the least risky option amid widespread public concern about the risk the Games will fuel new surges of infections.
Organisers have already banned overseas spectators and set a cap on domestic spectators at 50% of capacity, up to 10,000 people, to contain a lingering coronavirus outbreaks.
Officials have been wrestling with the question for months but a ruling party setback in a Tokyo assembly election on Sunday, which some allies of Prime Minister Yoshihide Suga attributed to public anger over the Games, had forced their thinking, sources said.
"Politically speaking, having no spectators is now unavoidable," a ruling party source told Reuters.
Japan will hold a general election later this year and the government's insistence that the Games - postponed last year as the virus was spreading around the world - should go ahead this year could cost it at the ballot box.
The Tokyo 2020 organising committee said restrictions on spectators would be based on the content of Japan's coronavirus state of emergency, or other relevant measures.
Japan has not experienced the kind of explosive Covid-19 outbreaks seen elsewhere but has seen more than 800,000 cases and 14,800 deaths. The capital, Tokyo, reported 920 new daily cases on Wednesday, the highest since May 13.
A slow rollout has meant only a quarter of its population has had at least one Covid-19 vaccination shot.
Preparations for the Games have been shrouded in concerns about the impact of Covid-19 as authorities have struggled to stamp out persistent clusters of infections, particularly in and around Tokyo.
On Thursday, the government is likely to extend restrictions in Tokyo and three nearby prefectures beyond an original end-date of July 11, government sources have said.
Kyodo News reported the extension would likely last a month, meaning the curbs will be in place throughout the Olympics, which begin on July 23 and close on Aug. 8.
The issue of spectators is due to be decided at five-way talks on Thursday, which will include the Tokyo governor and International Olympic Committee (IOC) President Thomas Bach.
Asked about the topic at a news conference on Tuesday, top government spokesman Katsunobu Kato said Suga has said holding the Games without spectators was a possibility.
Shigeru Omi, the government's top health adviser, told a parliamentary health committee on Wednesday it was important to reduce the number of Olympic officials and others attending events as much as possible.
Early July to September was "one of the most important periods" in combating the coronavirus in Japan, he said.
"We have been saying that it's preferable that the events be held without spectators," said Omi.
"We are asking many people to take steps to prevent further spread of the infection. Images of spectators would be sending out a contradictory message to a lot of people ... In formulating our coronavirus response, people's feelings are a very important factor."
In another blow to the Games, organisers announced on Tuesday they would ask the public not to gather on the streets to watch the marathon, one of the most popular events of the Games.
Tokyo authorities have also decided to move most of the torch relay, set to reach the capital on Friday, off public roads. Torch-lighting ceremonies without spectators will be held instead.
A torch bearer (L) running with the Olympic torch past spectators during the Tokyo 2020 Olympic Games Torch Relay in Yaizu, Shizuoka prefecture on June 24.