Tokyo, Japan (AFP): Last year's pandemic-delayed Tokyo Olympics cost 20 percent more than the final figure reported by the organising committee, according to an analysis by Japan's audit board.

A report issued late Wednesday found the Games cost 1.7 trillion yen ($12.9 billion), up from the 1.42 trillion yen reported by Tokyo 2020 earlier this year.

The audit board said organisers had incorrectly failed to include some Olympic-linked government spending on items including anti-doping measures, athlete training, Japanese food at the athletes village and the Olympic stadium.

And its report urged the government in the future to "reveal the total costs in a timely manner when it is substantially involved in a major event."

The 2013 bid for the Tokyo Games estimated the event would cost just 734 billion yen, but costs gradually ballooned, with a pandemic postponement adding to the bill.

Asked about the costs Thursday, government spokesman Hirokazu Matsuno told reporters "the government takes the points raised seriously and will respond appropriately", without offering details.

The Games were held a year later than planned because of the pandemic -- the first Olympics postponed in peacetime -- and spectators were banned from nearly all events, which were held under strict Covid-19 countermeasures.

Japanese prosecutors are currently investigating a string of bid-rigging allegations associated with sponsorship deals at the Tokyo Games.

On Thursday, a former executive of a major clothing company appeared in court on allegations of bribing a Tokyo 2020 official and admitted offering money to secure sponsorship rights for his firm, national broadcaster NHK said.

The corruption scandal has cast a shadow over the northern city of Sapporo's bid for the 2030 Winter Olympics.

Officials there this week announced they would stop holding promotional events for the bid and now hold a nationwide poll to gauge support.