Construction of Tokyo's new National Stadium for the 2020 Summer Olympics could cost up to ¥300 billion, Olympics minister Hakubun Shimomura said Wednesday.

Speaking at the House of Councilors Budget Committee, Shimomura said the government will consider scaling back the project because the estimated amount is "too massive."

The original plan called for the National Stadium, built in 1958 for the 1964 Summer Olympics with a capacity of 54,000, to be demolished and replaced with an 80,000-seat stadium complete with a retractable roof.

The envisaged cost includes ¥130 billion for work on the building itself, but Shimomura warned that fully realizing the streamlined design by London-based architect Zaha Hadid selected late last year could drive the cost up further.

Shimomura said he wants to focus on reducing the costs of work on the stadium's environs.

The government is aiming to have the work completed by March 2019 in time for the Rugby World Cup that Japan will host in September and October of that year.

The stadium is unfit to host the events of the 2020 Games in its present condition.

Shimomura heads an office set up early this month to coordinate preparations for the Olympics.