Published: Feb 23, 2011 6:01 PM EST
Updated: Feb 23, 2011 3:01 PM EST

WESTON- U.S. Drug Enforcement Administration agents and local police are making arrests in South Florida as part of an undercover investigation into illegal pill mills.

Federal law enforcement officials said Wednesday yearlong probe involved undercover purchases of painkillers and other prescription drugs, according to federal law enforcement officials. They spoke on condition of anonymity because details were to be announced at an afternoon news conference.

The investigation centered on pain clinics in Broward, Miami-Dade and Palm Beach counties. Arrests were expected to include doctors and pain clinic operators.

South Florida is the national epicenter for illegal dispensing of prescription drugs such as the painkiller oxycodone.

(Copyright 2011 by The Associated Press. All Rights Reserved.)