BERKELEY — A library watchdog group will protest the use of radio frequency identification tags — which it calls spy chips — during the Berkeley Public Library's gala authors dinner today.

Berkeleyans Organizing for Library Defense will gather in front of the library on Kittredge Street at 6 p.m. as people arrive at the $250-a-plate event, where more than two dozen Bay Area authors are expected, including Mark Danner, Judy Rodgers, Peter Coyote, Mary Roach and Deborah Santana.

The sold-out event, which this year includes dim sum, sushi and high-end vodka martinis, draws an elite crowd and raises thousands of dollars every year for the library. It is the library's biggest fund-raiser.

"We want them to know where their money is going and the effect that it's having on the library," said Gene Bernardi, a member of Berkeleyans Organizing for Library Defense.

Critics of the radio frequency identification devices say the tags, also used by other libraries, the government and even Wal-Mart as a tracking device, compromise the privacy of library patrons because, giventhe bar code, anyone can determine the name of a book.

"We are just really concerned about the potential for privacy invasion," Barnardi said. "Anybody who wants to badly enough can find out what (a) book represents."

Critics worry that if a person checks out a book on spying or the Middle East, for example, he or she could be unfairly targeted as a potential terrorist by the government.

They also worry that the library or anyone with the right scanning technology can link a book on, say, homosexuality, drug addiction or another private subject to a library patron who wants to keep his choice of library materials confidential.

Service Employees International Union Local 535, the union representing library workers, opposed the technology last summer and asked the City Council to research its cost, believed to be $2.5 million, Bernardi said.

Library Director Jackie Griffin disputes that, saying the total cost, including staffing, is about

$1.1 million.

Griffin said she does not feel a protest is appropriate on the library's big night.

"I really appreciate their concerns about privacy and the library, but I'm very proud of what the library has done to protect that privacy. Tonight is a night to celebrate the library and what we do and to celebrate the authors that make libraries possible," Griffin said.

There was little opposition to the technology when the library board approved it two years ago.

The library spent $650,000 on the system, and workers began installing the palm-sized tags last year. Library officials say the tags speed up self-checkout and free up valuable library staff to help with reference questions or other pressing library matters.

What's more, Griffin said there is nothing on the RFID tags that can connect an item to a patron. In fact, because patrons can check out materials by themselves, the system actually increases patron privacy, she said, adding that 62 percent of patrons are currently using the self-checkout system.