The only discernible health benefit of Walkers crisps is to the strength of Gary Lineker's bank balance, yet the snack firm is being lined up as a corporate backer of a high-profile drive by ITV to tackle Britain's obesity crisis.

Walkers Snack Foods is in the final stages of negotiations to be associated with Britain on the Move, a government-supported initiative that will involved a series of peak-time ITV programmes and features on regional news bulletins.

ITV said last night that the food company would not be a sponsor of the scheme, but would help fund the planned giveaway of 2m simple exercise machines called "step-o-meters". But child health campaigners attacked the move and said it sent out the wrong signals about diet. The broadcaster last year proposed Britain on the Move to the Department for Culture, Media and Sport, just as the culture secretary, Tessa Jowell, called on the media regulator Ofcom to tighten the "inadequate" rules on promoting junk food to children.

ITV and the food industry lobbied hard against tougher advertising codes, and there are suggestions that ITV used its commitment to Britain on the Move as leverage.

Ms Jowell has since softened her stance, saying she does not favour banning junk food adverts. She said last month: "We are getting fatter because we are less active. Of course advertising has an impact, but what we have to judge is whether [a ban] would be proportionate."

Walkers, part of Pepsico, is one of the biggest snack manufacturers in Britain, and has been criticised before for using Lineker in its promotions.

Kath Dalmeny, policy officer with the Food Commission, said yesterday: "Most children eat too many salty, fatty foods already. A 500ml bottle of Pepsi contains more sugar in a single serving than a 10-year-old should consume in a whole day. That's how excess unhealthy ingredients such as fat, salt and sugar get into kids' diets. But these products are presented as 'cool' and attractive."

ITV sources conceded yesterday that Walkers' involvement could cause problems with the scheme's other backers, such as Sport England and the British Heart Foundation.

The initiative starts on April 29; the broadcaster's regional websites are already promoting it. One says: "Obesity costs the public purse over £1bn every year and Britain is currently the most unfit nation in Europe with only 30% of people regularly active. We want to get Britain on the move -walking its way to health."

The campaign will launch with two programmes on April 29 at 7.30pm and 11pm on ITV1. The later programme will include a debate with MPs about how Britain can become a healthier nation.

A spokeswoman for ITV said Walkers was one of six potential associates for the scheme. "We are talking to all sorts of people - banks, supermarkets, chemists' chains. They would not sponsor the initiative itself, but would pay for the step-o-meters."

Walkers said no deal had yet been signed. A spokeswoman rejected suggestions that the deal could be open to criticism because of the health messages it sent out. "That's a completely different issue," she said.