A school has banned chocolate as part of a healthy eating drive.

Pupils at Whitehawk Primary School are being asked not to bring chocolate bars in their packed lunches.

If the youngsters are spotted with chocolate it is confiscated and replaced with a healthy alternative.

Teachers return the chocolate to the pupils at the end of the school day and then write to the children’s parents urging them to send their youngsters in with healthier food.

The rules were introduced after pupils carried out a survey of lunchboxes at the school after national research published by the Journal of Epidemiology and Community Health showed that 99 out of 100 packed lunches eaten at school are unhealthy.

Although the school did better than the national average – with more than half of lunches including fresh fruit and vegetables compared to just one in ten nationally – one in five packed lunches contained sweets, savoury snacks and sugary drinks.

While all schools must provide healthy school dinners, Whitehawk is believed to be the first in Sussex to ban chocolate from lunchboxes.

The school’s assistant headteacher, Annie Noble, who is the healthy schools co-ordinator, said: “We are trying to help with the children’s learning.

“We noticed some were beginning to bring in larger chocolate bars and they would have an initial high in the afternoon but would then plummet and become very irritable. This really affects their learning.”

Staff wrote to parents about the healthy eating initiative and provided ideas at parents’ evenings about what to put in lunchboxes.

Miss Noble said: “It is all about a balanced diet. Nobody minds if there is a balance between fruit, vegetables, carbohydrates and protein.

“The understanding is there, but in practise it is very difficult not to include sugary things in packed lunches. It is about helping the children and parents to make the right choices. Sometimes it is easy and sometimes it is difficult.”

The school already has a breakfast club and tuck shop.

Reporters from the school’s newspaper, the Whitehawk Primary Gazette, have been helping to spread the word about the changes.

A spokesman for the School Food Trust, an independent body which aims to transform school food, said: “Trying to bring packed lunches in line with healthy school dinners is a good step and as long as it is done sensitively it seems like the right thing for the school to do. Hopefully the parents will get behind it.”