KENT police are investigating a scam in which staff at petrol stations and a restaurant used hundreds of unsuspecting customers’ credit cards to commit fraud. Staff at two service stations and an Indian restaurant in Medway are suspected of copying the cards’ magnetic stripes and passing details to criminals making counterfeit cards.

Criminals either sell the fraudulent cards or use them to run up average debts of £2,000 each. Cards are “skimmed” by the employee who then jacks in the job after a month or so and disappears.

The counterfeit cards are not used until a few months later to allow the trail to go cold. Criminal gangs often swop card details skimmed in Kent with those from other parts of the country to further weaken the trail.

The first the genuine card holder knows is when his statement arrives.

Service stations and restaurants are the most likely venues for the crime because staff tend to be transient and low-paid.

Employees are either bribed or blackmailed to copy cards or are already in the criminals’ pay when they take the job.

Det Sgt Mark Fairhurst, of Kent police fraud squad, said: “There are 108 million credit and debit cards in the UK so it’s a medium open to abuse. Criminals are also becoming more aware of it and as their knowledge expands more and more of them are doing it.

“It’s a highly organised crime and our problem is that we tend to deal with the end user rather than the people producing the cards.”

He warned that the only way to prevent the crime was for all card holders to be more vigilant: “You should never let your card out of your sight. In a restaurant you should say that you will pay as you leave rather than let the waiter take your card away.

“After all, you wouldn’t put your entire card limit in cash on a plate and let it be taken away would you? But that’s what you’re effectively doing.”

Customers should also query petrol station cashiers who do not swipe their cards within full view, say police.

Det Sgt Fairhurst said: “While card holders do not directly pay for what the criminals spend, we all pay for it with higher interest rates and other charges.”

Last year, card fraud cost the UK £189 million. But in the 12 months to October 2001, the cost has rocketed by 54 per cent.

Counterfeit cards were also used by terrorists in the recent planning of an attack on Los Angeles airport before the September 11th atrocity.