Traces of cocaine have been found in a number of St Peter Port pubs and clubs following a BBC investigation.
A reporter using cocaine detection swabs found the drug in four out of the 16 bar and club toilets tested.
Guernsey Customs said it was working hard to stop drugs traffickers while acknowledging there was a demand for the drug on the island.
Tracey Rear, from Drug Concern, said it could be devastating if cocaine became as widespread as it was in the UK.
She said: "We tend to be 10 years behind the UK in terms of what people are taking.
"The UK does have a problem with crack cocaine particularly and it would have a disastrous affect if it got over from the UK."
Bookmark with:
What are these?