A company that operates a network of addiction treatment centers has agreed to pay $4.5 million to settle allegations that it charged the Massachusetts Medicaid program for unnecessary urine drug testing that was illegally performed at the company's own lab, officials said Thursday.

CleanSlate Centers, which operates more than 80 facilities in 10 states including 18 in Massachusetts, will pay $3.2 million to the state and $1.3 million to the federal government, the company and the state attorney general's office said in separate statements.

"As we face a worsening opioid crisis in Massachusetts, it's important that treatment centers follow the rules and not cut corners to increase their bottom line," state Attorney General Maura Healey said. "Our resolution with CleanSlate will bring millions of dollars back to the state and implement the oversight needed to protect patients and prevent these violations from happening again."

Tennessee-based CleanSlate, which includes former U.S. Rep. Patrick Kennedy on its board of directors, denies any wrongdoing, liability or violating any laws, CEO Greg Marotta said in a statement.

"We have chosen to settle this case due to the severe economic impact a prolonged legal battle would have had on the thousands of individuals and families we serve," he said.

CleanSlate has served nearly 40,000 Massachusetts residents since 2009, and wants to focus on its primary mission.

"We will continue to work relentlessly with the Commonwealth to provide access to mental health and addiction treatment," he said. "We are committed to moving forward from today's resolution to help more Americans reclaim their lives."

In its original federal lawsuit filed in October 2020, the Massachusetts attorney general's office alleged that CleanSlate and its former owner charged MassHealth, or companies that manage care for its patients, $54 million. The state did not determine how much of that billing was fraudulent.

The state alleged that CleanSlate required some patients to submit to a variety of urine drug tests, some of which were medically unnecessary, causing false claims to be submitted to MassHealth.

The state also said CleanSlate clinicians were directed to refer laboratory work to its own Holyoke laboratory, a violation of federal and state self-referral statutes.

The original complaint also alleged that the former owner engaged in practices that led to backdating of prescriptions for Suboxone — a drug used to treat opioid addiction — resulting in the submission of false claims.

The settlement not only resolves the state's federal lawsuit, but a whistleblower suit brought by a former CleanSlate employee, the attorney's general's office said.