The U.S. Department of Justice Wednesday announced a lawsuit accusing CVS of filling and billing federal health insurance programs for illegal opioid prescriptions, contributing to a nationwide epidemic of opioid addiction and overdose.

The newly unsealed complaint in Providence, Rhode Island federal court alleges that, from October 2013 to the present, CVS filled prescriptions for dangerous quantities of opioids and dangerous combinations of drugs and provided early refills, violating the federal Controlled Substances Act.

The Justice Department said the violations were driven by company-mandated performance metrics, and that in some cases patients died of overdoses shortly after filling illegal prescriptions.

"We have cooperated with the DOJ's investigation for more than four years, and we strongly disagree with the allegations and false narrative within this complaint," CVS said in a statement.