A Hertfordshire pub has sent out a strong anti-drugs message to its customers by inviting police in to carry out checks.
Drugs tests were carried out on 53 customers at the Otter in Bushey using a portable testing kit known as the Itemiser with three people testing positive.
Searches were then carried out on those with positive readings, but none were found to have illegal substances on them.
Customers were forced to take a test as a condition of entry, and a spokeswoman for Hertfordshire Police said everybody was happy to comply.
The test works using swabs which are wiped across a person's palm. The swab is then placed in the Itemiser machine, which gives a result within seconds.
The machine, which is also used by the military and customs officers, can test for up to 200 different types of drugs including cocaine, heroin, cannabis, amphetamines and ecstasy.
Sergeant Nick Caveney of Hertford-shire Police said: "The positive readings show that the person has physically come into contact with illegal drugs it does not mean they have ingested the substances. It may be that they have unintentionally been in contact with someone who handles drugs, or surfaces that have drug traces on them.
"If the Itemiser detects traces of drugs, it gives the police grounds to carry out a search of the person to see if they are in possession of controlled substances.
"This was a good opportunity for police to work with the licensee and staff of the Otter, sending out a clear message that taking or supplying of drugs will not be tolerated on the premises."
Lorraine Andrews, licensee at the Otter, said: "It's an excellent initiative that hopefully will put people off attempting to bring drugs into pubs right across the area.
"We are very happy to have the police here working with us. We are a family pub and we want to keep it that way."