RENO - The past president of the American Medical Association opposed a proposed $2.6 billion health care merger in Nevada on Thursday, saying the ``robber barons'' behind it have a record of putting profits ahead of patients.

Several nurses and other health care practitioners also testified before the Nevada Insurance Commission against UnitedHealth Group Inc.'s buyout of the Las Vegas-based Sierra Health Services Inc. Company officials tried to reassure regulators that Sierra Health would retain its own leadership and expand services without raising rates.

The nearly three-hour hearing in Reno came after concerns were raised by the state attorney general's Bureau of Consumer Protection earlier this week that the acquisition ``may result in the most concentrated insurance market in the country.''

Dr. William Plested, immediate past president of the AMA, said it's part of a trend he called a ``tragedy, a travesty _ the malignantly explosive growth of giant, for-profit monopolies that provide health care.''

``UnitedHealth has an unblemished record of putting profit over patients,'' Plested said.

``These are not just the good old boys from Lake Wobegon. These are the robber barons of the modern era.''

Diane Ross, executive director of the Reno health and wellness center Continuum, said UnitedHealth reimburses health care providers at rates lower than Medicaid and Medicare while providing poor customer service.

``With UnitedHealth yesterday, we got Kevin in India,'' she said about a telephone call to inquire about reimbursement.

``Then we got somebody else and then we were hung up on,'' Ross said. She tried to call back but wasn't able to reach someone who could help. ``This is not unusual and not unique.''

Critics say the merger would put a single entity in control of 80 percent of the HMO market in Nevada.

Corporate officers said that's misleading because there is no distinct HMO market in the state, rather it's a sector of an overall insurance market. They said they would control less than 30 percent of Nevada's commercial health insurance market.

``The marketplace is extremely competitive in Nevada,'' said Frank Collins, vice president and general counsel for Sierra, which operates Health Plan of Nevada, the state's first and largest HMO.

``I can assure you as a result of the merger there will be no increase in the rates,'' added ...