The Food and Drug Administration on Tuesday warned nine companies for illegally making powerful prescription drugs used to treat severe pain.

The FDA said the companies should stop manufacturing the products within 60 days if they want to avoid further enforcement action. The FDA sent the warnings to Xanodyne Pharmaceuticals Inc., Cody Laboratories Inc. and Mallinckrodt Inc. Pharmaceuticals Group, a unit of Covidien Ltd. (COV), among others.

The drugs involved contain morphine, a powerful painkiller, and hydromorphone or oxycodone. The FDA's move doesn't relate to approved versions that contain these ingredients, said Deborah Autor, director of the office of compliance within the drug division of the agency.

Tuesday's announcement is part of a broader investigation by the FDA to keep unapproved drugs off the market. Since the FDA began in 2006 to keep unapproved products off the market, the agency has targeted more than 200 companies and 500 products, Autor said.

"It is a high priority for the FDA to remove these products from the market because they may be unsafe, ineffective, inappropriately labeled, or of poor quality," said Janet Woodcock, an FDA director, in a statement.

The FDA said the announcement won't result in drug shortages for people who need to take the pain medicines, as there is adequate approved versions of these drugs on the market.

The FDA said consumers concerned about whether they are taking unapproved versions of these drugs should contact their physician and consult the FDA's unapproved drugs Web site at http://www.fda.gov/cder/drug/unapproved_drugs/.

-By Jared A. Favole, Dow Jones Newswires; 202-862-9207; jared.favole@dowjones.com