Which? assessed the nutritional content of items that fit into children’s lunch-boxes and found some were “full of salt and sugar”.

The Which? report found that one pack of Dairylea Lunchables Ham ‘n’ Cheese Crackers contained 1.8g of salt – more than half the recommended daily allowance of a four to six-year- old, and that a 200ml Robinsons Fruit Shoot orange juice drink contained 23g of sugar, which equals almost five teaspoons.

Which? is calling for robust rules on when products can make health and nutrition claims to help families pick out healthier food.

Which? magazine editor Martyn Hocking said: “Some products give the impression of being healthy but are full of salt and sugar.

“The best way to beat the lunch-box baddies is by checking the nutrition and ingredient information.

“We’d also like to see the rules on health and nutrition claims made tougher so that there’s less confusion on the supermarket shelves.”