Tokyo Games organizers on Wednesday admitted to throwing away approximately 4,000 of the 10,000 pre-ordered bento boxes full of food that was to be fed to volunteers on the day of the opening ceremony.

Masanori Takaya, a spokesman for the organizing committee, confirmed the report and apologized in a press conference at the main press center.

"On the day of the opening ceremony at the Olympic Stadium, the large number of staff on duty meant that all of the volumes were large, and a lot of the food was not consumed," Takaya said.

He explained that due to the heavy workload for volunteers they did not have a chance to eat the food, which was set to be turned into animal feed and used for biomass power generation.

Takaya revealed that there has been an approximately 20 to 30 percent surplus of food across all venues, particularly on July 23, the day the games opened.

He promised to optimize ordering processes and to ensure volumes procured better correspond with what will be consumed to prevent waste.

With cardboard beds and recycled metal used in the medals, the Tokyo Games aim to be the most environmentally friendly ever. Organizers have emphasized the importance of sustainable practices under the slogan: "Be better, together -- for the planet and the people."

Carbon emissions, energy, waste and food are among the environmental topics included in the Tokyo 2020 Sustainability Plan.

"Everyone can contribute to reducing food loss. Think of the word 'mottainai,' and let's try not to waste food," the official website of the Tokyo Games writes. "Mottainai" is a Japanese expression of regret when something is used wastefully.