Clad in matching blue polo shirts emblazoned with the Olympics logo and grey waist pouches, volunteers of all ages stood around the cavernous Tokyo International Forum chatting and taking photos.

When not watching the weightlifting, others sat on chairs in the corridor, playing with their phones.

"I wanted to be a volunteer because I was born in the year of Tokyo's first Olympics. But to be honest, I don't have much to do here," said one 57-year-old woman who was supposed to be offering translation services.

She applied for the position three years ago and went through a series of interviews and tests.

"Without fans, maybe we can serve as fake spectators. In any case it is a good opportunity to see how things work at the Olympics and enjoy the events for free."

The woman, like others interviewed, declined to be identified because volunteers aren't allowed to speak to the media.

At the Forum, located in the heart of the city not far from the Imperial Palace, the venue appeared to be still set up as if spectators were expected, with signs pointing to spectator seating and medical services for fans.

"Volunteer roles are currently being reassessed," Tokyo 2020 said in response to questions from Reuters.

One official said that organisers hadn't reduced the number of volunteers because they didn't want to cause disappointment.

The unsung heroes of the Olympics, volunteers are a rich part of its tradition and serve as translators, guides and drivers.

They range from university students to retirees and usually come from all over the world.

Some 110,000 were initially planned to help in Tokyo, although 10,000 had quit as of last month, as the worsening pandemic turned public opinion against the Games.

Most foreign volunteers are also not being let in because of the pandemic.

There are now around 80,000 volunteers, Tokyo 2020 said, not including those managed by the Tokyo government.

Volunteers were provided with their uniforms, including shoes and socks, from official sponsor Asics Corp, and told to wear them to and from the venues, the man said.

Meals were free and they were paid 1,000 yen ($A12) a day for transport, he said.

Some volunteers at the Tokyo International Forum stood around by the entrance, appearing to block the way for others coming in and out.

One man, seconded to the venue by his employer to help during the Games, said it was overstaffed and difficult to know what people were supposed to be doing.

"There are just too many people here including volunteers," he said. "There are even volunteers who clean the cafeteria used by volunteers."

Australian Associated Press