The warning follows a series of raids on counterfeiters across West Yorkshire which netted more than £250,000 worth of fake goods.
Operation Santa Claws swooped on shops, market stalls and illegal street vendors over three successive days in Leeds city centre, Chapeltown, Dewsbury and Bradford.
The raids were carried out as part of a joint operation between police and Morley-based West Yorkshire Trading Standards Service.
Brand
The haul included counterfeit clothing and footwear bearing fashionable brand names often sold at what are comparable to high street prices but of inferior quality and finish.
Yesterday's raid on traders Leeds city centre also netted dozens of fake watches. including Rolex, DNKY, Betty Boop and Diesel as well as Arsenal and Manchester United football watches.
Paul Smith, of West Yorkshire Trading Standards Service, said the items seized during the three-day operation were of very sub-standard quality.
"People may think they are buying a genuine item, such as a branded watch, when in fact they are poor quality fakes which will only last a few months at best," he said.
"Those involved in the supply of counterfeit goods are often seen by the general public as likeable Arthur Daley types. But the reality is very different and behind the fake goods is serious organised crime."
Mr Smith said the latest 'must have' Christmas present to attract the attention of the counterfeiters were iPod nanos.
"We recently seized a batch which have the full packaging and look like the real thing. But when you take them out of the box they are a completely different design and they don't work properly," he said.
Graham Hebblethwaite, West Yorkshire's chief trading standards officer, said: "This operation is a warning message to traders that we will not tolerate the illegal sale of counterfeit goods.
"Previous raids in the area have resulted in traders being sentenced and receiving custodial sentences as well as being ordered to forfeit all goods seized and to pay substantial costs for the sale of counterfeit goods."
andrew.hutchinson@ypn.co.uk