Tokyo Olympics facing six-fold blowout

Unexpected road infrastructure and materials costs are being blamed for a reported mass blowout in staging the 2020 Tokyo Olympics.

Artist rendering provided by the Japan Sports Council shows the inside of Design "A" proposed by one of two groups competing to build the new Tokyo Olympic stadium Source: AAP

The 2020 Tokyo Olympics will reportedly cost the organising committee six times more than the original estimate at 1.8 trillion yen $US14.85 billion.

Citing sources familiar with the matter, public broadcaster NHK said on its website on Friday the blowout was caused by unexpected payments for building lanes on highways, as well as rising materials costs and personnel expenses.

The Tokyo 2020 Organizing Committee will only be able to raise about 450 billion yen from sponsors and ticket sales, which means a shortfall of more than 1 trillion yen, the report said.

The committee had earlier estimated a cost of 300 billion yen for the Summer Games in 2020, but that was optimistic, said NHK.

Total costs for staging the Tokyo Olympics, estimated to be more than 2.1 trillion yen, will be shared by the committee, the Tokyo government and national government.