A McDonald's restaurant has been built in the London Olympics Park (Reuters)

A children's charity has branded London 2012 the "Obesity Games" in a campaign calling for sporting events to crack down on junk food sponsorship.

In an 11th-hour request, the Children's Food Campaign, which is run by Sustain, has called for the International Olympic Committee to re-examine its sponsorship deals with companies such as McDonalds, Coca-Cola and Cadbury's.

The charity claimed that corporate sponsorship accounted for 2 percent of the games' total income and therefore could be cut. It said the use of unhealthy food for sponsorship squandered any chance the games had to give a positive message to young people.

A petition has been launched for delivery to Locog chairman Sebastian Coe, calling on him to make it clear in the official post-games report that "accepting money from unhealthy companies [was] counter-productive to good public relations and to a positive health legacy".

"The Olympics have become a celebration of 'big'. For the junk food companies who sponsor the games that means big restaurants, big audiences, big brand value, big profits," said Malcolm Clark, campaign co-ordinator.

"But for the children that could also mean bigger waistlines and bigger health problems later in life. Yet the one thing about the Olympics which is not big is the proportion of revenue from sponsorship.

Healthy choice the harder choice

"The International Olympic Committee could choose to cut out the top-tier category of food and soft drink partners entirely and lose little more than 2 percent of its total income."

Clark added: "At every turn, the sponsorship of the Games - from the companies selected, to the terms of the deals agreed, to the way that they are implemented - seems to be set up to make the healthy choice a harder choice.

"It's time that the IOC took responsibility for the effect of its sponsorship programme and made the necessary changes."

The charity created posters which show how much exercise would be needed to burn off junk food. A Big Mac meal would take 110 minutes of cycling to brun off and a 500ml bottle of Coca Cola is the equivalent of 25 minutes of playing tennis, it said.

It also pointed the finger at the scale of advertising afforded to the companies, such as the Coca Cola Torch Relay and the Cadbury's Gingerbread House in Hyde Park.

McDonald's said sponsorship was "essential" to the staging of the games and that it was proud of its involvement.

Coca Cola said: "People consume many different foods and drinks, so no one single food or drink alone is responsible for people being overweight or obese. We believe all of our drinks can be enjoyed as part of an active, healthy lifestyle that includes a sensible, balanced diet and regular physical activity."

London 2012 Olympic Games: Most Britons Can't Name Single Sponsor

Two Thirds of Very Obese Children under 12 Are already on Road to Heart Disease.