Thousands of Japanese erupted in joy early Sunday as they learned Tokyo would host the 2020 Olympic Games.

Some had risen very early, while others had stayed up all night to hear the decision from Buenos Aires, which came at 5:20 am local time.

Several broadcasters had live coverage of the event, with public broadcaster NHK having begun its programming at 10.30 pm on Saturday.

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As Olympic chief Jacques Rogge read the IOC decision, cheers and shouts rang out, with groups of ecstatic Japanese hugging each other and punching the air.

TV hosts and their guests were temporarily speechless and several were in tears, with some making reference to people living in the area affected by the earthquake-tsunami and the nuclear emergency it caused in March 2011.

At the Tokyo Chamber of Commerce and Industry, where around 1,200 people had gathered to watch live-streaming of the announcement in Buenos Aires, people held V signs aloft and cheerleaders hugged each other. Some shouted "Banzai" (hurrah!).

At the MC's prompting, the crowd in unison said "arigato" (thank you) to Buenos Aires.

At Komozawa Olympic Park in the south of Tokyo, which served as a venue for several sports at the 1964 Tokyo Olympics, golden tinsel rained down at the moment of decision.

A boisterous crowd held signs and chanted "Tokyo, Tokyo, Tokyo, Tokyo," as an interviewer fought to be heard above the din.

When he finally got his question out -- "What do you think of the news?" -- one man shouted: "It's the best!" before they all resumed chanting and cheering.

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

At the Chamber of Commerce, the evening had kicked off with around 200 people, from the Tokyo Metropolitan Government, the Tokyo Olympic bid committee, sponsors and sporting heroes watching live coverage of Tokyo's final presentation to IOC members in Buenos Aires, half a day away.

The crowd enthusiastically applauded each speech and presentation made by Tokyo representatives including Princess Takamado, Prime Minister Shinzo Abe and Japanese Olympic committee president and IOC member Takeda.

NHK's all-night program including excerpts from presentations by the three cities, scenes from the vote venue and the three candidate cities, and interviews with Olympic medalists.

Private networks began similar live programs at around 3:00 am.

By 4:00 am numbers in the hall had swelled to 1,200, and it was standing room only. Around 20 TV crews were there to witness the moment.

By the time the news came through, it was light in Tokyo and television coverage was showing no signs of ending.