Missouri on Wednesday became the third US state to accuse major drug manufacturers of fraudulently misrepresenting the risks of opioid painkillers now at the center of a national addiction epidemic.

Missouri Attorney General Josh Hawley said his office filed a lawsuit in a state court in St. Louis against Purdue Pharma LP, Johnson and Johnson and units of Endo International Plc.

Hawley said the three companies knew their opioid products were addictive and potentially life–threatening, but "engaged in a deliberate campaign of fraud to convince Missouri doctors and consumers otherwise."

"They used bogus front organizations and fake research; they used fraudulent advertising and deceptive trade practices," Hawley said in remarks prepared for a news conference. "And they repeatedly lied about the true risks of the drugs they sold."

Hawley said the lawsuit accuses the companies of violating Missouri's consumer protection laws and its Medicaid statutes and seeks hundreds of millions of dollars in damages and civil penalties.

The case made Missouri the third state to sue drug manufacturers over their opioid marketing and sales practices. Last week a bipartisan group of state attorneys general announced an investigation.

Purdue, Johnson and Johnson and Endo were previously sued in similar lawsuits by the Ohio and Mississippi attorneys general, who also targeted Teva Pharmaceutical Industries Ltd and Allergan Plc.

Opioids, including prescription painkillers and heroin, killed more than 33,000 people in the United States in 2015, more than any year on record, according to the US Centers for Disease Control and Prevention.

Johnson and Johnson's Janssen Pharmaceuticals unit said in a statement it acted appropriately and responsibly, adding that its opioid pain medications were approved by the US Food and Drug Administration and carry mandated warnings about their known risks.

Purdue, which manufactures OxyContin, said it denied the allegations but shared Hawley's concerns about the opioid crisis and was "committed to working collaboratively to find solutions."

Endo declined to comment on the lawsuit, but said its "top priorities include patient safety and ensuring that patients with chronic pain have access to safe and effective therapeutic options."

The FDA this month asked Endo to withdraw its long–lasting opioid painkiller Opana ER from the market.

Beyond the states' cases, similar lawsuits have been filed by local governments, including two California counties; the cities of Chicago and Dayton, Ohio; three Tennessee district attorneys; and nine New York counties.

—Nate Raymond