Image copyright Reuters Image caption Mori said at a send-off ceremony that athletes who did not sing properly did not deserve to represent Japan

Japan's Olympic team has been warned by the president of the Tokyo 2020 organising committee not to "mumble" the national anthem.

Those who did not sing properly did not deserve to represent the country, said Yoshiro Mori, a former prime minister with a history of gaffes.

He was speaking to 300 athletes at a send-off ahead of the August Olympic Games to be held in Rio de Janeiro.

Reports say attendees had just sung Kimigayo, Japan's national anthem.

"When you go up to the podium, please do not be mumbling but sing the national anthem," Mr Mori told those gathered on Sunday.

"Athletes who cannot sing the anthem should not be considered to be Japan's representatives," the Asahi newspaper reports him as saying.

Mori, who served as prime minister from 2000 to 2001, is well known for his off-the-cuff remarks.

In February 2014, he claimed that English was the "enemy's language", when asked why he spoke Japanese instead of English while addressing an international audience.

Image copyright Getty Images Image caption Yoshiro Mori previously came under fire for criticising figure skater Mao Asada's performance at the Sochi Olympics

He also came under fire after he criticised Japanese figure skater Mao Asada's performance at the Sochi Olympics.

The Tokyo 2020 Olympic and Paralympic Games has also met with controversy - its first choice of logo was thrown out when the designer was accused of plagiarism and the design for the main Olympic stadium had to be scrapped because of spiralling construction costs.