Brown is convinced fruit can bring “radiance,” a spokesman said, while declining to confirm a report in the Sun that the premier is scoffing the fruit as an alternative to his favourite KitKat bars.

Brown is gearing up for an uphill battle to hold on to power against the main opposition Conservatives, in elections due before June but expected on May 6.

“The prime minister has always taken the view that a balanced diet is very important,” Brown’s spokesman told reporters on Monday, neither denying nor confirming the banana story.

He added: “Portions of fruit and veg taken on a daily basis can only lead to good health and radiance.”

Questioned about the amount of fruit Brown was eating, he said that any numbers were pure “speculation”.

Bananas have been risky political accessories since Foreign Secretary David Miliband was snapped brandishing one two years ago, in a photo that was widely mocked and undermined his hopes of leading the ruling Labour party.