TOKYO (AFP) - Millions of voters in Tokyo will elect their new governor in February, the mega-city said on Wednesday, after the resignation of the previous incumbent over a money scandal.

The gubernatorial election is set for February 9, a Sunday, with ballots to be counted on the same day, the city's election board said.

Candidates must formally declare themselves on January 23 during business hours.

No-one has put their hat in the ring yet, but possible candidates being mentioned in the media include Hideo Higashikokubaru, a comedian-turned-politician who resigned as a lower house member this month, and education minister Hakubun Shimomura.

Flamboyant former premier Junichiro Koizumi has declined to run after minor opposition grouping Your Party asked him, according to the Mainichi daily.

Koizumi, who will turn 72 in January, has emerged as a high-profile critic of Japan's nuclear power industry, despite his pro-nuclear record in office.

He has urged his one-time protege and the nation's current leader Shinzo Abe to abandon atomic power.

Naoki Inose, 67, who had been one of the main faces of Tokyo's successful bid to host the 2020 Olympics, submitted his resignation last week, admitting he had been naive to accept an undeclared US$500,000 (S$634,120 )from a hospital tycoon.

Inose was elected head of one of the world's biggest conurbations a year ago with a record 4.34 million votes, inheriting the mantle from firebrand nationalist Shintaro Ishihara.

But he had faced weeks of intense pressure over the money, which critics implied amounted to a bribe and an attempt to influence policy.

Tokyo's governor is the most senior politician in the metropolis of 13 million people including the city proper, semi-rural districts and even some islands many hours away by ferry from the neon city.

He has overall charge of an annual budget of more than $60 billion for an area that has a GDP larger than that of Indonesia.