Noble Foods has lost "tens of thousands" of potential customers this week after it was forced to delay an ad campaign for eggs because the children's song it featured was found in breach of rules banning kids making health claims.

The soundtrack featured the song Chick Chick Chick Chick Chicken, with the lyrics adapted to include the phrases 'lay a healthy egg for me' and 'I've never had an egg so tasty. And it's Omega-3'.

However, Clearcast, formerly the Broadcasting Advertising Clearance Centre, said it could not use the voices of kids in the ad to sing those lyrics. The company was forced to re-record the £1m ad with one adult voice, replacing the phrases with 'lay a little egg for me' and 'why not have a free-range egg', delaying the campaign by a week, so it aired just one day before Pancake Day - its biggest day of the year.

In a policy statement on kids in food ads, Clearcast said: "Children may not be used to make nutritional claims, deliver a sales message or otherwise comment on aspects of food that could not be expected to be of interest to them.''

Noble Foods said it was outraged by the decision. "Mums should be encouraged to give kids eggs to eat as they're cheap and healthy," said marketing director Finn Cottle. "It seemed so appropriate to have children singing this catchy tune. We missed the opportunity to show the ad in the week leading up to the single day of biggest egg penetration."

However, Clearcast defended the move. "Omega-3 is something children of the age used in the ad wouldn't talk about, said editorial standards manager Kristoffer Hammer.

Kids were not banned from food ads altogether and each case was looked at individually, he added.

Clearcast's decision is the second time in eight months it has intervened in an egg advert.

Last June, it banned the revival of the 1950s Tony Hancock 'Go To Work On An Egg' campaign, saying it went against the principle of a varied diet.