Three in four children’s snacks which claim to contain “one of your five a day” do not contain a full portion, a study has found.

Researchers said parents who were trying to find healthy fare were being confused by labels which portrayed foods as nutritious when they were loaded with sugar or salt.

The study by the University of Glasgow analysed 322 products marketed to children, including juices, yoghurts, cereals, cereal bars and fruit snacks.

Almost half made claims about contributing to a child’s “five a day” requirements, but most such claims did not stack up, the study found.

Among those which said they contained at least one portion of fruit or vegetables, three in four did not contain the recommended 80 gram portion size.

Calling for stricter regulation of labelling and marketing, researchers warned that such claims created a “health halo” distracting parents from the fact many such snacks were full of sugar.

They warned that the heavy use of cartoon characters, designed to appeal to children, and misleading health claims aimed at parents, is fuelling Britain’s obesity crisis.

One in three children are overweight or obese by the time they leave primary school, along with two in three adults.