"They are saying the Games are more sustainable and there is way more plant-based food but sometimes if you go at peak times it's challenging to even get a piece of chicken," the Times of London quoted one British athlete whose name was withheld as saying.

Andy Anson, chief executive of the British Olympic Association said the food "is not adequate."

"There are not enough of certain foods: eggs, chicken, certain carbohydrates, and then there is the quality of the food, with raw meat being served to athletes," Anson said.

"They have got to improve it over the next couple of days dramatically," he said.

He said that British athletes are shunning the main dining hall.

"Our athletes have decided they would rather go and eat in our performance lodge in Clichy, so we are having to get another chef to come over as the demand is far exceeding what we thought it would be," he said.

"The athletes are not going there just to eat their lunch, they are packing meals for their dinner as they don't want to go into the athlete restaurant to eat. So we are trying to make sure our athletes have an advantage by having more food. It is the biggest issue at the moment," he said.

A French-language publication said Sodexo, which is feeding the athletes, has said it will make more food available that meshes with what athletes need.