Statewide mental health provider South Bay Mental Health Center, which serves tens of thousands of vulnerable patients, a number of them in Dorchester, fraudulently billed the state Medicaid program by providing services through unlicensed, unqualified, and unsupervised employees, according to a lawsuit filed against the company by Attorney General Maura Healey.

The Brockton-based medical center, now named South Bay Community Services, has been serving about 30,000 MassHealth members at 17 clinics across the state since the fall of 2009.

All 17 clinics listed in the federal lawsuit had “significant gaps” in required licensing and supervision, the suit alleges, including employees without the required degrees in social work.

Of the roughly $123 million requested and paid out by the state to South Bay during that time frame, a “significant portion” was based on fraudulent claims, Healey said. The attorney general’s’ office is seeking unspecified treble damages, civil penalties, and prejudgment interest.

“This company provided substandard care to many vulnerable patients and fraudulently billed the state for its inadequate services,” Healey said in a statement. “MassHealth members deserve competent treatment from qualified individuals, and our office will continue to take action in order to remove these significant barriers to accessing critical mental health care in our state.”

After a whistleblower lawsuit was filed by a former South Bay employee in Aug. 2015, Healey’s office began investigating the health center network. The investigation, the attorney general’s office said, found “a widespread pattern” of employing unqualified staff, in violation of MassHealth restrictions. Submitting Medicare claims for their services using unacceptable employees is a violation of the Massachusetts False Claims Act, according to Healey’s office.

South Bay Community Services, in disputing Healey’s claims, said in a statement that it “does not agree with the allegations and intends to follow the legal steps necessary to resolve this matter as efficiently as possible. We remain focused on the well-being of our consumers and employees.

Our daily operations have not been affected, and we will continue to provide the best possible behavioral health services to those who need it most in the New England area.”

A South Bay satellite clinic located at 415 Neponset Ave. is listed in the suit for numerous licensing problems. Of the at least 30 individuals known, only a handful were independently licensed, the suit alleges. The regional director was not licensed, and the clinic director was not independently licensed until 2014.

“There were no independently licensed supervisors at the Dorchester Clinic who held their licenses for their entire tenure,” the lawsuit reads. “The majority of staff therapists at the Dorchester Clinic were unlicensed and could not have been adequately supervised as required... given the lack of qualified supervisors at the clinic.”

The lawsuit further alleges that the Dorchester Clinic billed MassHealth for services provided by unlicensed clinicians who were not being appropriately supervised and while the clinic was operating with an unlicensed clinic director.