Ishihara is set to leave office in 2011, a few months before the official bids are submitted, but is still expected to influence the city's decision.

"Tokyo will apply for it once again. We have taken all the trouble to build up the momentum. Tokyo must apply for it," Ishihara said in an interview with the influential newspaper Asahi Shimbun.

Rio became the first South American country to win the right to host an Olympics when the International Olympic Committee chose it over Tokyo, Chicago and Madrid on Oct. 2.

Tokyo said it had spent some 15 billion yen (US$165 million) on the bid, which featured a plan to stage compact and "green" Olympics by reducing carbon emissions from Games-related projects and operations.

The Olympic bid was one of key projects for Ishihara, a 77-year-old outspoken novelist-turned-politician, whose third four-year term in office will end in early 2011. He has repeatedly said he will not run for another term.

"It is my responsibility to declare our candidacy," Ishihara said. "It is up to the next governor to decide whether or not we will act it out."

Hiroshima and Nagasaki, two Japanese cities that were hit by U.S. atomic bombs in the closing days of World War II, said last month they were considering a joint bid as part of their campaign to promote a nuclear-free world.

Ishihara said Tokyo could offer to embrace Hiroshima into its bid.

The International Olympic Committee is expected to select the 2020 host city in 2013 based on bids submitted in the middle of 2011.