SACRAMENTO — Atty. Gen. Dan Lungren advised state officials Thursday that California law requires State Board of Equalization member William Bennett to step down from his $95,000-a-year post because of his conviction on a charge that he filed false expense reports.

Lungren said technically Bennett's seat has been vacant since Feb. 21, when he pleaded no contest to a misdemeanor that involved a "violation of his official duties."

He said Gov. Pete Wilson is free to immediately appoint a replacement, a move that is expected to pave the way for Republicans to assume majority control of the powerful tax board. Bennett is one of three Democrats who sit on the five-member board that hears appeals of state income tax cases and oversees the collection of billions of dollars in sales and other business taxes.

"There is no question that the statute is very specific with respect . . . to an action involving official activities," Lungren said. "Suspension from office takes place immediately upon entry of the plea."

James Lee, a spokesman for Wilson, said the governor believes that the Lungren opinion gives him the "legal basis for considering the seat vacant." He said the governor will move as quickly as possible to name a replacement.

But Bennett's attorney, James Brosnahan of San Francisco, said his client has not decided if he will step down from the post or force the attorney general to seek legal action to have him removed.

Brosnahan said he did not agree with the attorney general's opinion and doubted that the courts would accept his legal reasoning.

"Remember, no court in California has ever removed an officeholder for a misdemeanor involving events which occurred during a prior term," he said. "I think that's central and important and I think it casts a very dark shadow on the legitimacy of the opinion."

The charge against Bennett involved a June, 1988, travel claim for which he collected reimbursement. The state contended that the claim filed by Bennett included expenses for hotel costs that Bennett never incurred.

In return for Bennett's plea of no contest to the single misdemeanor count, Sacramento County Dist. Atty. Steve White agreed to drop a 23-count felony complaint that had accused Bennett of filing numerous other false claims.

A Municipal Court judge ordered the 74-year-old officeholder to pay a $1,000 fine, to reimburse the state $5,500 and to perform 200 hours of community service.