And one in 10 thought Britain's favorite fried food was made from oil, eggs, flour or apples.

The findings are revealed by the British Heart Foundation, which is campaigning to make children more aware of what is in their food.

Gristle, Bones and Connective Tissue

Its Food4Thought blitz, launched today by ITV sports presenter Gabby Logan, includes stomach-churning posters showing what goes into chicken nuggets, burgers and hot dogs.

The graphic billboards feature lumps of gristle, bones and connective tissue, claiming they are "common ingredients" in fast food.

The BHF hopes to make children think about what they eat and encourage them to make healthier diet choices. Director General Peter Hollins said: "Our research sends a shiver down my spine. Kids no longer know what they are eating. We must help them understand why some foods are healthier than others."

The BHF predicts half a million children will be diagnosed as overweight or obese within two years.

It wants a ban on fast food and fizzy drink advertising which targets them and the return of domestic science to the school timetable.

Asthma Attacks in Children

Stars including England cricket hero Andrew Flintoff, girl band Girls Aloud and Cold Feet actress Fay Ripley are backing the campaign.

Mum of one Fay said: "The BHF is right to challenge children this way."

Eating burgers more than once a week almost doubles the risk of asthma attacks in children, research on 1,300 pupils in New Zealand shows.