Japan is on the hook to pay as much as $US50 million ($A67.41 million) for its scrapped Olympic stadium even though not a single brick has been laid.

The revelation comes days after Prime Minister Shinzo Abe said the country was going “back to the drawing board” amid a growing chorus of complaints over the $US2 billion price tag for the planned centrepiece of Tokyo 2020.

Tokyo is committed to paying “most” of around 5.9 billion yen $US50 million ($A67.41 million) worth of contracts already awarded in connection with the ditched design, according to major media, citing data from the Japan Sport Council which oversees the project.

And, reports warned, that figure could rise if contractors file lawsuits.

Iraqi-British architect Zaha Hadid’s futuristic design had been met with fury by many Japanese architects, with commentators complaining it looked like a bike helmet and would be disproportionately large.

But the swelling cost attracted the most ire, with original projections far outstripped by recent estimates.

“Most of the money has already been paid, so the scrapping of the existing stadium construction plan is expected to (mean) the money is wasted,” Kyodo News said.

Chief Cabinet Secretary Yoshihide Suga said the government would launch an independent panel to study why the issue became such a problem but he refused to assign blame.

“Our focus is to put all our efforts into a new plan, following the prime minister’s decision. Time is limited,” he told media.

Yoshiro Mori, a former prime minister who heads the organising committee for Tokyo 2020, said he hoped the new stadium would serve the Japanese public for decades to come.

He reiterated, however, that construction costs in Japan are higher than in many other countries.

“People say it cost only 46 billion yen to build the stadium in Beijing,” he told reporters.

“Can you compare the labour cost in Beijing and Tokyo, and say that’s a fair comparison?”