Car breakers in the South West say they are being targeted by criminals seeking to avoid paying congestion charges in central London.
Criminals have visited breakers' yards to get vehicle details
Vehicle dismantlers in the region are reporting a marked increase in car cloning since the charges came in.
The practice involves using the number plates of scrapped vehicles to avoid being caught for not paying the charge.
Transport for London, which operates the charge, has made more than 100 arrests in connection with car cloning.
Drivers going into the congestion charge area of London have to pay £5 per day by telephone, text message, post, internet, or in person at a retail outlet.
The scheme is policed by cameras on roads around the centre of the city which read car registration plates.
If, by the end of the day, people fail to pay the congestion charge, then a fine is issued.
But if false number plates are used, that fine never reaches its intended destination.
The first staff at Kirton Motor Spares in Crediton, Devon, knew of any criminal activity was when they got a phone call from Scotland Yard.
Graham Holmes said: "They told us that they'd caught a gentleman with a vehicle the same colour and with the same registration number as one we had.
"Apparently he'd been a previous customer of ours who had come down from Wales to buy parts from for another vehicle."
Chief Inspector Ian Aspinall of Devon and Cornwall Police said: "I've no doubt it has increased the problem of cloned number plates.
"But anyone who has cloned a plate just to save a few bob on going through London really has to question why they are doing it.
"The penalties are really severe and they'll end paying a lot more than just a £5 congestion charge if they get arrested."
Transport for London said it was working closely with police to keep such vehicles off the road.