CORAL SPRINGS, Fla. (AP) _ A doctor was charged with illegally distributing prescription drugs that were used in the overdose deaths of up to 20 people.

Dr. Barbara Mazzella, 61, was held Friday on federal charges of illegal drug sales, conspiracy to sell drugs and scheming to defraud Medicare, Medicaid and private insurance companies.

``The charges are serious but they're not proven,'' said Ms. Mazzella's attorney, Jeffrey Harris. ``She denies breaking the law and she's a physician of good standing in the community.''

In an arrest affidavit, investigators said three of Ms. Mazzella's patients have been arrested for selling prescribed drugs on the black market. One reseller was prescribed 5,422 doses of pain killers and was caught in 1998 after selling pills to an informant, authorities said.

An undercover agent who accompanied a patient to Ms. Mazzella's office noted that the patient received four prescriptions from the doctor on every visit, the affidavit said. Each time, the patient paid $100 for a visit that consisted only of a blood-pressure examination, the affidavit said.