Tokyo on Saturday won the right to host the Olympic Games for the second time, overcoming fears about radiation from the stricken Fukushima nuclear plant to land the 2020 edition of the world's biggest sporting event.

Members of the International Olympic Committee (IOC) meeting in Buenos Aires chose the Japanese capital, which previously hosted the Games in 1964, over Istanbul, after Madrid was dramatically eliminated following a first-round tie with the Turkish city.

Thousands of Japanese who gathered in Tokyo in the early hours of Sunday erupted in joy, making V for victory signs and shouting "banzai!" (hurrah!), as the result was beamed live from the Argentine capital nearly a dozen time zones away.

At the Tokyo Chamber of Commerce and Industry, crowds shouted "arigato" (thank you) in unison, several television hosts and their guests were lost for words and in tears, while at the Komozawa Olympic Park -- venue of several sports at the 1964 Games -- golden tinsel rained down in celebration.

"I have been waiting a long time for this feeling," bid chief Tsunekazu Takeda said in Buenos Aires. "The members of the IOC have seen that Tokyo is a safe pair of hands."

Tokyo city governor Naoki Inose added that the Olympics would help Japan recover from the devastating 2011 earthquake and tsunami that claimed more than 18,000 lives and vowed no let up to create what he said would be "the best Games ever".

Japan's Prime Minister Shinzo Abe had earlier flown to South America from the G20 summit in St Petersburg, Russia, to reassure nervous members about the safety of the nuclear plant some 220 kilometres (140 miles) from Tokyo amid fears about the leaking of contaminated water.

He told delegates that the situation was "under control", adding: "It has never done or will do any damage to Tokyo."

Fukushima operator the Tokyo Electric Power Co also played down fears of a possible spread of radiation in a separate message.

Concerns over Fukushima -- seriously damaged by the quake and giant waves two-and-a-half years ago -- had dogged the bid in the final days but Abe successfully allayed IOC members' fears.

The final result was 60 votes for Tokyo against 36 for Istanbul.

Tokyo -- third in the vote for the 2016 Games won by Rio de Janeiro -- had been the frontrunners originally, as they promised a safe and financially secure Games in what they termed "uncertain times".

The decision means it will be the fourth time that Japan plays host to the Olympics, having also organised winter Games in Nagano (1998) and Sapporo (1972).

Asia will see successive Olympics as the South Korean resort of Pyeongchang is hosting the 2018 winter edition.

Madrid had looked to be the city with the momentum coming into the final week after an outstanding presentation to IOC members in Lausanne in July -- and were hoping that like Rio de Janeiro for the 2016 race, they could go on to win.

But it was not enough, even with 28 of the 35 venues built and all the infrastructure in place plus a positive assessment by the IOC Evaluation Commission -- the only IOC members allowed to visit the bid cities -- over their relatively low budget.

Doubts about Spain's recession-hit economy persisted to the end and not even some more upbeat news on the issue recently and Prime Minister Mariano Rajoy's pledges that financing would not pose problems convinced enough members that they could deliver.

Istanbul had been hoping Turkey would become the first predominantly Muslim country to host the quadrennial sporting extravaganza.

But despite a passionate and dynamic campaign trading on bridging two continents and two cultures as well as an evocative "wake up in Asia compete in Europe" slogan, their bid was hampered in June.

Several IOC members were unimpressed by the heavy-handed way that the Ankara government handled anti-government protests that escalated from opposition to the redevelopment of an Istanbul park.

There was also nervousness surrounding the fallout from the bloody civil war in neighbouring Syria.

Prime Minister Abe said in his presentation that the Olympics were part of his DNA, having experienced them for the first time at a young age.

"I was at the opening ceremony in Tokyo in 1964 and saw several thousand doves all released into the clear blue sky and coming together to make the Olympic rings," he said.

"It was all amazing to me at 10 years old.

Like Inose, he also cited his experience meeting one of the children on a trip to visit survivors of the earthquake and tsunami, and said sport had a key role in society to aid recovery.

"I met with one boy in the affected area, he was holding a cherished football, given to him by a footballer from overseas who had visited the area," said Abe.

"That ball was not just a football to him, it represented his hope for the future.

"Today under the blue sky of Fukushima there are young boys playing football and looking into the future and not the past."