Children are not being given nutritious food in their packed lunches, according to a study by mysupermarket.co.uk.

The website's 'school lunchbox nutrition study' claimed that parents are "obliviously" packing their children's lunchboxes with foods "laden" with fats, saturates, salt and sugar but low in nutrients.

A typical lunchbox, consisting of a ham sandwich, a packet of crisps, a fun size chocolate bar, a yoghurt and a piece of fruit, contains around 40g of sugar, 4.45g salt and a total of 760 calories, the survey said.

Despite these findings, 65% of parents still believe their children have a well balanced diet, and just 2% admit their child's diet is unhealthy.

The results come at a time when the NHS has revealed that childhood obesity can lead to a number of disorders including type 2 diabetes, high blood pressure, social exclusion, and even depression.

Dr. Mabel Blades, independent dietician and nutritionist, said: "What children and teenagers eat has an impact on their health, behaviour and ability to learn. It is a shame if young people having a packed lunch miss out on balanced nutrition.

"The information means that "treats" such as crisps or biscuits can still be included occasionally but ones with a more nutritious content can be selected. Also easy comparisons can be made with other alternatives such as different types of fruits."

On a regional basis, parents in the Midlands think that their children's diet is the worst in the country, with well over a third (39%) admitting that they would describe it as unhealthy. 

Northerners (30%) are the second most likely to think their children's diet is poor, closely followed by Wales and the South West (29%) and Scotland and Northern Ireland (27%.)

Miranda Watson, food campaigner at Which? said: "We are constantly being told by parents that it's really hard to work out the difference between good, everyday lunchbox options and treats because food labelling is so poor. Many treats are marketed directly to children and dressed up as ideal for lunchboxes. It's time for the food industry to help parents, help their kids."