TOKYO (Reuters) - International Olympics officials said on Thursday that they were "hugely impressed" by Tokyo's bid to host the 2020 Olympic games as well as strong government support from a country keen to show it has recovered from the devastating 2011 quake and tsunami.

International Olympic Committee (IOC) Vice President and chairman of the IOC Evaluation Commission Craig Reedie of Britain (2nd L) shakes hands with wheelchair tennis player Shingo Kunieda of Japan after the presentation of the Tokyo 2020 bid to host the Summer Olympics to the commission at Ariake Tennis Park in Tokyo March 4, 2013. REUTERS/Yuya Shino

At stake are an estimated three trillion yen (21 billion pounds) in potential economic impact and the chance, Japanese officials say, to showcase the country's recovery from the disaster in the way the 1964 Tokyo Summer Games highlighted the nation's return after its World War Two defeat.

"We have been hugely impressed by the quality of the bid presentations made by the bid committee," said Craig Reedie, vice president of the International Olympics Committee (IOC).

"Across the board, they have just been excellent," he told a news conference.

Reedie declined to give details, but did single out strong support both from the government and from the business community. Among those making presentations during the evaluation committee's four day visit were Prime Minister Shinzo Abe and Fujio Cho, the outgoing chairman of Toyota Motor Corp.

But Japanese media noted that Tokyo had received early praise during its failed bid to host the 2016 games, which it lost to Rio de Janeiro, and Tokyo governor Naoki Inose warned against any complacency.

"This is about at the halfway point of a marathon," he told a news conference. "The most crucial time is now. We must keep running this marathon for the next six months."

Tokyo is up against Madrid and Istanbul, both of which have also bid for the Games and lost before. A decision will be made on September 7 in Buenos Aires.

ALREADY BUILT, SENTIMENTAL APPEAL

In Tokyo's favour are the fact that many of its venues are already built. Tokyo planners also emphasize the compactness of its offer, with 85 percent of the venues located within an 8 km (5 mile) radius of the Olympic Village.

The jewel in Tokyo's campaign is a space-age makeover of the National Stadium, the main venue for the 1964 Games. The 80,000-capacity venue, which resembles a flying saucer.

The Tokyo government estimates that the Games would increase demand by 1.22 trillion yen in tourism, sales of Olympic goods and household spending. With private sector investments included, the total impact is likely to hit 3 trillion yen nationwide and include the creation of 150,000 jobs.

The government has gone to considerable effort to emphasise the sentimental possibilities of a Tokyo games, including holding some of the football playoffs in Miyagi, part of the country badly devastated by the 2011 disaster.

"Tokyo 2020 will inspire many others, just as Tokyo did before in 1964," Abe, who has been appointed as the bid's supreme adviser, told the committee at the start of their visit on Monday. The 1964 Games were the first Olympics in Asia.

Tokyo bid officials have acknowledged concerns about the potential for another earthquake but emphasize Japan's strict building codes, noting that there was minimal damage in Tokyo from the 9.0 magnitude 2011 quake.

In a nod to Japan's trademark high-tech, officials on Thursday unveiled a mobile drug testing laboratory that will aid monitoring for sports whose locations are not easily accessible.

The mobile lab includes a toilet and a lab to test urine samples, and has been accredited to analyse the samples right there in the van.

Though Tokyo lost its previous bid in part due to low public support, an IOC survey published this week found that some 70 percent of respondents want Japan to host the games.

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