While most workers compensation fraud arrests are workers accused of defrauding insurers, district attorneys in two California counties have charged senior insurance company officials with trying to defraud workers.

Fraud statutes treat workers and insurers the same, saying it's unlawful to lie ''to obtain or deny'' benefits.

In each case, the officials are accused of withholding information that could have meant higher benefits.

The San Diego District Attorney's Office claims a senior fraud investigator and a senior claims adjuster at Cigna Insurance Co. covered up information that would have helped an injured worker but would have damaged her employer. The case is scheduled for trial this month.

The Fresno District Attorney's Office alleges that two senior Fremont Compensation Insurance Co. executives altered documents to make it appear they had paid injured workers and doctors on time, when they had not. Both pleaded guilty to one felony count of offering false evidence.

''We apply the law equally wherever insurance fraud is involved,'' said Dominic Dugo, assistant chief of the insurance fraud division at the San Diego County District Attorney's Office.

Prosecutions also are picking up against employers, since a law was passed in 1995 requiring the reporting and investigation of premium fraud.

"In terms of dollar costs, there's no question that employer fraud today costs more dollars to carriers and to the industry than employee fraud," said Richard Schultz, a spokesman for State Compensation Insurance Fund, the state's largest workers compensation insurer.

Premium fraud usually is when employers try to avoid paying their premiums.

They may lie to insurers about the size or nature of their work force or funnel their injured workers to health insurance to avoid rising workers comp premiums.

In an odd twist, it's fraud when an employer is underinsured on purpose. But it's not fraud when an employer has no insurance at all. California taxpayers spend almost $25 million a year to take care of workers who were injured while working for uninsured employers.

The insurance industry claims that fraud by employers costs insurers as much or more than fraud by workers.

Nevertheless, workers are the focus of most fraud prosecutions.

California district attorneys reported that out of 1,505 investigations they conducted in fiscal year 1995-1996, 1,220 were workers and 88 were employers. They also investigated 120 medical providers and 15 alleged medical-legal mills, but not insurers.

The California Department of Insurance reported that out of 202 arrests it made in the same year, 119 were workers, 21 were employers, 11 were medical providers and 16 were from medical-legal mills, but none were insurers.