Revellers in Weston-super-Mare are being warned not take illegal substances into pubs and clubs as police unveil a new weapon in their fight against drugs.
On Saturday, officers visited two clubs in the town with a hi-tech device which can detect if people have been in contact with drugs.
The "Ion Track Itemiser" lets out an alarm if cocaine, heroin, amphetamine, ecstasy or cannabis are detected.
It tests a piece of card which contains a swab taken from a person's hand.
Sergeant Dave Holtby said: "We have carried out some tests already, but have made no arrests so far.
"The Itemiser will find even the smallest traces of drugs on people.
"It was very noticeable that some groups who would have come into the clubs on the night decided not to when they realised what we were doing."
Traces of drugs were found on seven of the 378 clubbers tested on Saturday.