TOKYO — An expert panel commissioned by Japan’s capital city has warned that the total cost for the Tokyo 2020 Olympics could exceed $30 billion unless drastic cost-cutting measures are taken.

The panel on Thursday said the ballooning costs reflect an absence of leadership and a lack of governance and awareness of cost control.

The Olympic investigation panel, led by Shinichi Ueyama, a Keio University public policy professor, was launched by newly elected Tokyo Gov. Yuriko Koike as part of broader reforms after she raised concerns about ever-growing unofficial cost estimates and the potential burden on the city.

The report reviewed three out of seven permanent venues that Tokyo is planning to build, and proposed using existing locations rather than new facilities that could end up being white elephants.

The estimated $30 billion is more than a four-fold increase from the initial estimate at the time of Tokyo’s successful bid for the games in 2013. Organizers have not released their official estimate.

Tokyo organizing committee president Yoshiro Mori acknowledged in July 2015 that the total cost could exceed $20 billion, doubling his unofficial estimate a year earlier.

“Naturally, anyone who hears these numbers is alarmed,” Ueyama said.

The report said facilities based on overestimated capacity for stadiums, use of unnecessarily high-grade equipment and lack of budget ceiling have driven up the scale of design and cost.

The panel also said legacy use prospects for the big new permanent facilities are also overly optimistic considering Japan’s declining population and aging society.

To cut costs, the report proposed moving the rowing and canoeing venue away from Tokyo and renovating existing facilities for two other sports.

Preparations for the games have been plagued by a series of scandals, including the new national stadium’s high cost and design, and allegations of bribery in the bidding process.