Federal health officials are investigating allegations that California's Medicare watchdog organization committed fraud by falsely certifying that it had reviewed thousands of patients' hospital records. The investigation, launched last month, focuses on charges made by sources at California Medical Review Inc. that the company billed the government for approving more than 30,000 records it had not examined, during a three-month period in 1986, sources told the Associated Press. California Medical Review is a nonprofit, physician-sponsored group paid by the U.S. Department of Health and Human Services. A spokeswoman for the firm said it is aware of the investigation but denied any wrongdoing. "We have always and will continue to conduct our reviews appropriately," spokeswoman Sharon Ahern said.