The blue light makes is difficult to see a vein

Sainsbury's has installed the lights at its Huntingdon store.

The blue light prevents veins from showing up on arms and are being used deter drug-injecting users.

The lights are common in nightclubs, bars, service stations and a small number of other stores.

There are dealers (in Huntingdon) who are dealing £3,000 worth of class A drugs each day

Cambridgeshire Police spokesman

A Cambridgeshire Police spokesman said Huntingdon had a known drugs problem and was being targeted with a special operation to reduce drug taking.

"Any initiative which helps our fight against drug-taking is to be welcomed," said the spokesman.

"Although Sainsbury's is not known as a place for drug users, the town does have a problem with heroin and other hard drugs like crack cocaine.

Solved the problem

"There are dealers who are dealing £3,000 worth of class A drugs each day."

The blue lights have also been fitted in the town's Woolworth's store, where they have deterred drug users.

A spokesman for the store added: "Historically there has been a problem with drug users using several retailers' toilets in the town. The blue lights have completely solved the problem.

"It was a decision taken at local level at the store where a problem was identified."