Ed Balls challenges George Osborne to run the London Marathon

Ed Balls threw down the gauntlet when he found out the Chancellor is also following the 5:2 diet

Labour MP and Shadow Chancellor Ed Balls gives a thumbs up as he poses with his medal after the Virgin London Marathon 2013. (Peter Macdiarmid/Getty Images)

Not content with competing over who will help to run the country after the 2015 election, Ed Balls has challenged George Osborne to join him in running the next London Marathon.

The Shadow Chancellor proposed the pair go head-to-head in the race after he discovered that Mr Osbourne also follows the popular 5:2 diet, The Sun reported.

Mr Balls told the newspaper: “George Osborne sponsored my last two marathons for Action for Stammering Children and Whizz-Kidz. Now he's trying to get in shape, maybe he'll join me this year.”

The Labour politician completed the 26-mile run in 2012 and 2013, despite vowing that he'd never enter the race again after his first attempt.

In the 2013 race, Mr Balls beat his previous personal best of 5 hours and 31 minutes by 17 minutes, and raised £100,000 for charity.

“It was a great feeling running down the Embankment with the crowd cheering, and up The Mall to complete the course. But the euphoria only lasted so long before the pain really set in,” he said before the 2013 race.

“My whole body ached for days. No surprise, then, that in the days and weeks afterwards, the phrase ‘never again’ was constantly on my lips. And yet, one year on, I’m ready to run the marathon again," he added.

Labour sources told the newspaper that the Chancellor, who is currently in Sydney for a G20 meeting, is yet to respond.

The 5:2 diet requires the men to limit themselves to a 600 calories for two days of the week, while they can eat the normal recommended amount of calories for the rest of the days.

Mr Balls' challenge comes after Mr Osborne has repeatedly made jokes about what he sees as Communities Secretary Eric Pickles' rotund appearance during speeches at the Tory Party conference.