A growing number of casinos are relying on more than video cameras and pit bosses to catch cheaters. They are using radio frequency identification (RFID) technology — tiny tags embedded in gaming chips that can spot counterfeiters and track thefts, as well as help tabulate gamblers' spending habits.

The tags, which have drawn complaints from privacy advocates when used in supermarket retail items, are similar to bar codes but so small they can be placed into almost any object. They also can hold much more information and do not have to be in open view of a scanning device.

"You'll see it start to take off in the next year to two years, and then become widely popular in the next four- to six-year time frame," predicted David Lopez, vice president of product development for Shuffle Master, a Las Vegas company that is among those developing the technology for casinos.

Gambling-industry officials said the technology offers more security by alerting dealers and cashiers when the value of the tokens in front of them does not match the amount scanned. Although chip counterfeiting is relatively rare, a casino in Reno, Nev., lost $26,000 last year in one scheme.

Las Vegas' Hard Rock Casino began experimenting with RFID chips at some blackjack tables several months ago. The new Wynn Las Vegas casino also has used them since opening in April.

Casinos in other states — including Louisiana's Coushatta Casino Resort and Minnesota's Grand Casino Hinckley and Grand Casino Milles Lacs — have been using the chips over the past year, as have others in Canada and abroad.

The emergence of RFID in casinos has stoked the broader debate over whether the technology is intrusive. It has been used in suitcase tags to help airlines find lost luggage, in merchandise at Wal-Mart and other stores, and in the E-Z Pass quick-payment system at highway toll booths.

"With RFID technology, as with many other surveillance technologies, we need to consider how it will be used, and will it be effective," Sen. Patrick Leahy, D-Vt., a leading voice on privacy issues, said in a speech last year. "What information will it gather, and how long will that data be kept? Who will have access to those data banks, and under what checks and balances?"

Katherine Albrecht, founder and director of Consumers Against Supermarket Privacy Invasion and Numbering, said she fears casinos could use the technology to secretly sort customers.

"If you've got a pocketful of chips, it could be possible to identify who has a lot of money and who has nothing," Albrecht said. "If you're down to $33, they may not offer you that free drink. But if it's $3,800, they might offer you a drink that's twice as strong."

Gambling-industry officials say RFID scanning works only across short distances, making surreptitious scanning of customers virtually impossible. They also say the data are unavailable to anyone outside a casino.

But they said RFID does enable casinos to precisely track bettors' habits to assess their eligibility for "comps" — free meals and other perks.