SACRAMENTO (AP) -- State officials are temporarily suspending 16 California alcohol and drug treatment centers suspected of violating health care laws -- from hiring people who were convicted of abusing patients to bilking Medi-Cal for services they never performed.

Department of Health Care Services Director Toby Douglas said Thursday he is referring the centers to the state Department of Justice for further investigation. Douglas oversees Medi-Cal, the state's Medicaid health insurance program for the poor.

"There have been reports of abuse and fraud in the Drug Medi-Cal program and we took action," Douglas said in a statement. "We are in the midst of a wide ranging statewide investigation."

The state issues about 1,000 licenses to provide treatment to Medi-Cal patients for substance abuse and addiction. State officials began investigating 22 treatment centers and found 16 were suspected of various violations.

Some centers are suspected of hiring people who have been convicted of defrauding the government or neglecting or abusing patients. Others are being investigated for performing unnecessary procedures or fraudulently billing the Medi-Cal drug program.

The state declined to identify the centers and will not pay them until the investigation is complete.

Lynda Gledhill, a spokeswoman for Attorney General Kamala Harris, confirmed Thursday that the department is reviewing the case.