Wholesalers were plagued by a return of widespread duty fraud to the beer market at Christmas as crooks circumvented tougher rules on duty drawback.

Several leading wholesalers have revealed that their trade was hit by a rise in the amount of non-duty-paid beer on the market, particularly in London.

Beefed up requirements came into effect on 1 April 2007 demanding more information from traders using the drawback system.

They must now provide the clearest possible evidence that the goods are UK duty-paid. However, it is believed criminals are getting round this by moving goods between bonded warehouses in a complex scam that makes it harder to keep track of products.

"With these fraudsters, whenever we close one avenue they will immediately look to try another route," said FWD director general John Murphy. The FWD would continue to work closely with HMRC and suppliers to tackle the issue, he added.