A corruption scandal surrounding last year's Tokyo Games has damaged Japan's bid to host the 2030 Winter Olympics, a top local official warned.

Sapporo, in Japan's northern island of Hokkaido, had been seen as the frontrunner to host the Winter Games for a second time, ahead of Salt Lake City and Vancouver.

But Hokkaido governor Naomichi Suzuki believes an investigation into allegations of bribery in the selection of Tokyo Games sponsors is threatening to derail Sapporo's bid.

"When you consider the series of problems related to the Tokyo Olympics, it will be difficult to build momentum with things as they are," Suzuki said.

"I want the truth to come out as soon as possible. Unless we have thorough discussions and counter-measures to gain people's understanding, we won't be able to take things forward."

As part of their investigation, Japanese police arrested Haruyuki Takahashi, a former Tokyo Games executive, on suspicion of taking bribes in return for helping companies become official event sponsors.

The scandal has also engulfed the company that produced soft toys of the Games mascots, as well as a suit retailer, a publishing firm and major advertising agencies.

And former prime minister Yoshiro Mori, who resigned as Tokyo 2020 president after making sexist comments, volunteered to be interviewed by prosecutors in September.

The 2020 Games were pushed back to summer 2021 because of Covid.

Earlier this month, the International Olympic Committee decided to postpone selecting a host for the 2030 Winter Games, citing concerns about the impact of climate change.

The host city was originally due to be chosen in autumn 2023.

Hokkaido governor Suzuki said he still believes staging the Games would benefit the region.

"We will decide how to proceed, along with the Japan Olympic Committee and the city of Sapporo, who are leading the bid," he said.