With still so much uncertainty, Japanese Olympics sponsors are getting jittery.

According to sources they are cancelling or scaling back booths and promotional events tied to the Tokyo Games.

They're frustrated by "last minute" decisions by organisers.

And the delay over whether spectators would be allowed.

The moves are thought to involve more than a dozen companies including Canon and Ajinomoto.

Around 60 Japanese companies paid more than $3 billion for sponsorship rights.

Organisers have already banned overseas spectators and planned a cap on domestic fans at 50% of stadium capacity, or up to 10,000 people.

Some sponsors have reportedly scrapped plans to set up promotional booths along the "Olympic Promenade".

The area on the Tokyo waterfront was supposed to be open to spectators and non-ticket holders.

But organisers have urged spectators to travel directly to and from venues without any detours.

Sportswear maker Asics called off a planned public unveiling of a monument to Japanese table tennis star Kasumi Ishikawa.

The company worried that it would attract a crowd.

Sources says sponsors have also downgraded entertainment and party plans for clients and top executives.

Some are also worried about bad publicity if their executives are shown on live television in the stadium.