A school headteacher has defended a decision to co-operate with a supermarket on banning children from its store, after criticism on social media.

Sainsbury's in North Walsham has banned all children wearing North Walsham High School uniform from entering its store.

It follows several incidents of shoplifting at the store by pupils this week.

Kathryn Wiseman, who has a 12-year-old daughter at the school, said on Twitter: 'Nothing like punishing the many for the actions of a few.'

But headteacher Neil Powell said it was a 'very short-term measure'.

He said: 'This is only until we can demonstrate to the supermarket that 99.9pc of our children are incredible. We will take some of the pupils into the store next week to talk to people there. It will not take more than a week/10 days.'

A letter has been sent to parents explaining the school's actions.

The letter says: 'It is most unfortunate that a small minority of students wearing the uniform of the school and therefore representing the school chose to attempt theft of items from Sainsbury's supermarket.

'These students have tarnished the reputation of the school and its standing in the community and have brought the school into disrepute.

'Following a meeting with the Sainsbury's store management, the action decided upon by both the store and the school is to prohibit any students wearing the uniform of North Walsham High School from entering Sainsbury's North Walsham unless in the company of a responsible adult.

'No student is to enter the store in their school uniform unless this condition is met.

'The management and staff of Sainsbury's North Walsham will ask any unaccompanied students to leave the store.

'Any further instances of theft or attempted theft will be investigated by the security team of the store in conjunction with the police.

'Where evidence is found to support allegations of theft or attempted theft the school will take swift and decisive action in dealing with any students involved.'

A Norfolk police spokesman confirmed that it was investigating a theft at the Bacton Road supermarket on March 13.

Sainsbury's was unavailable for comment.