(Reuters) -The U.S. Justice Department's criminal division is digging into business practices at UnitedHealth Group's pharmacy benefit manager, Bloomberg News reported on Tuesday, citing people familiar with the matter.

Under an ongoing probe into the company's operations, the investigators are looking into its prescription management services and how it reimburses its own doctors, the report added.

Pharmacy benefit managers like UnitedHealth's Optum Rx negotiate drug prices and create coverage lists for health plans, mainly for employers and the government. They pay pharmacies directly for prescription drugs under their agreed terms.

UnitedHealth is under investigation by the U.S. DoJ over its Medicare business, a U.S. government program that covers medical costs for individuals aged 65 and older and those with disabilities.

The company said in July it is complying with both criminal and civil requests from the federal agency.