The flame, kept at a sports training facility in the south-western Japanese city of Kagoshima, has been dubbed as an "Olympic sacred flame".

It came to prominence again when Tokyo was awarded the 2020 Summer Olympics and Paralympics.

However, it has now been reported that the flame went out in November 2013, two months after Tokyo won the Games in Buenos Aires.

It was hastily relit, the then head of the facility told Agence France-Presse (AFP).

"At that time, I could not say something that could destroy [people's] dreams," the official, who wished to remain anonymous, said.

"I saw with my eyes that the flame went out on November 21.

"We relit the fire and kept it going for about two weeks, but I thought that was not good.

"At that time, there was considerable media interest in the flame as Japan had just been awarded the 2020 Games.

"In addition, we kept receiving a number of requests from various people to use the 'sacred flame' for town festivals and weddings. 

"I decided to come clean."

Local Kagoshima official Mitsuru Horinouchi also told AFP that the flame was extinguished for good in November 2013.

The facility now keeps a different flame - ignited by a magnifying glass and sunlight in December 2013 - at a camp site.

"We now have a display panel explaining that the existing flame was created after the flame from the 1964 Olympics went out," the current head of the facility, Etsuko Tabata, said.

Yoshinori Sakai, who was born in Hiroshima on the day the first atomic bomb devastated the city, lighted the Tokyo 1964 Olympic flame in the Japanese capital's main stadium.