KitKat, Dairy Milk and Mars are among major brands planning to cut the size of their chocolate bars to meet government targets on reducing sugar.

The move will avoid the manufacturers being named and shamed in a series of Public Health England reports on child obesity, the first of which will be published in March.

Firms are currently under pressure to reduce the amount of sugar in their products, and while many high-sugar products such as fizzy drinks, breakfast cereals and yoghurts can be reformulated using artificial sweeteners, chocolate makers complain that this ruins the taste.

Manufacturers have offered to reduce the size of their chocolate bars by 20 per cent, according to the Sunday Times, the amount by which Public Health England wants sugar content to be reduced by the end of the decade.

These include Mars, Nestle, which owns KitKat, and Mondelez, the American company which owns Cadbury.

However, they have not said whether they will reduce prices for the smaller products.