This legislation, enacted at a plenary session of the House of Councilors of Japan, establishes a legal framework for anti-doping measures - something which Tokyo 2020 President Yoshirō Mori says has been "called for globally, and will boost anti-doping activities in Japan".

It will also make it possible for the Japan Anti-Doping Agency, the Japan Sport Council and public authorities to share information and implement anti-doping measures more effectively.

"With the help of related parties, we will continue our best effort to prepare for a Tokyo 2020 Games where athletes can compete on a level playing field," Mori said.

The passing of the law comes less than a month after two-time backstroke swimming world champion Junya Koga was removed from the Japanese squad for the Asian Games after failing a drugs test.

The failure marked another blemish on Japan's previously good anti-doping record in the build-up to Tokyo 2020.

Tokyo bid officials claimed in 2013 that no Japanese athlete had been implicated in a doping scandal in the latter stages of a contest against Istanbul and Madrid - bids from two countries who had each faced a multitude of failures.

But Japanese kayaker Yasuhiro Suzuki was banned for eight years in January after he admitted spiking a rival's drink with an outlawed substance.

Suzuki laced Seiji Komatsu's bottle of water with an anabolic steroid to ensure he failed a drugs test at the Canoe Sprint Japan Championships last year.

Japanese short-track speed skater Kei Saito then became the first athlete embroiled in a doping scandal during the Winter Olympic Games in Pyeongchang in February.

Saito failed an out-of-competition test for banned masking agent acetazolamide on February 4 and was withdrawn from the Games without competing.

In another boost for Tokyo 2020 today, the Japanese Parliament has enacted a law to move some national holidays to days linked to Tokyo 2020 Olympic Ceremonies in an attempt to ease traffic congestion in the Metropolitan area.

Kyodo News reports that under the revised law, July 23, the eve of the Games, July 24, the day of the Opening Ceremony and August 10, the day after the Closing Ceremony, will be made holidays for 2020.

A number of important guests, including foreign dignitaries, are expected to travel to and from Japan on those dates.

"The resulting inclusion of special measures in the Japanese Radio Law and in current national legislation governing public holidays takes into account the likely impact of the Opening Ceremony on people’s schedules, and is a significant step towards the smooth implementation of the Tokyo 2020 Games," Mori said.

"We would accordingly like to express our gratitude to everyone who has worked on this legislation.

"We will continue to work with all related parties with the aim of hosting a smooth and safe Games."

A recent study warned that Tokyo hosting the 2020 Olympic and Paralympic Games could cause "fatal congestion" on the Japanese capital's famed subway system.

The study, conducted by Professor Azuma Taguchi of Tokyo's Chuo University, also claimed some of the key lines on the network could be "paralysed" during the event because of overcrowding.

Stations near to Games venues will be the most affected, according to Taguchi, who predicted a 10 to 20 per cent increase in the number of passengers at major transfer points.

Concerns over congestion on the subway network in Tokyo have been exacerbated by the high volume of commuters who use it already on a daily basis, with carriages heaving full of passengers a regular occurrence.

The study, which used mathematical model to predict the flow of passengers on a hypothetical day during the Olympic Games, said 1.3 million fans could add to the eight million commuters on the network, raising additional challenges for the system.