The U.S. Drug Enforcement Administration said on Friday it is inspecting six Walgreens pharmacies and its distribution center in Florida, after the agency noticed a jump in purchases of the highly addictive pain killer oxycodone.

The DEA issued inspection warrants on Wednesday to Walgreens’ distribution center in Jupiter and to stores in Hudson, Port Richey, Oviedo, Fort Myers and two stores in Fort Pierce, said Mia Ro, a spokeswoman for the DEA in Miami.

Under the U.S. Controlled Substances Act, a warrant may be issued for “valid public interest” and without the type of probable cause needed under criminal law, according to the warrant filed in U.S. District Court, Middle District of Florida.

“DEA is investigating Walgreens Jupiter and its top six retail pharmacies in Florida for 2011 to determine if the pharmacies are dispensing controlled substances outside the scope of their registration in violation of federal laws and regulation,” the warrant said.

For instance, in 2009 there were no Walgreens retail walk-in pharmacies listed in the DEA’s top 100 purchasers of oxycodone for retail pharmacies in Florida. By 2011 there were 38 and 53 in just the first two months of 2012, the warrant said.

In another example, a Walgreens in Ft. Myers, which purchased its oxycodone from the Jupiter wholesale distribution center, accounted for 67 percent of that drug purchased by all the pharmacies in the same zip code.

“The purchase of large amounts of oxycodone by a retail pharmacy is indicative of a pharmacy that fills prescription issued by physicians at pain clinics and/or a pharmacy which services primarily drug seeking individuals that abuse the medication,” the warrant said.

The action follows DEA’s recent move to suspend Cardinal Health’s license to distribute controlled substances — drugs that are susceptible to abuse — from its facility in Lakeland, Florida, and also intervened to prevent two CVS Caremark Corp pharmacies in Florida from selling controlled substances. The companies are fighting the orders in court.

“We are working with, and cooperating with, the DEA on this matter,” Robert Elfinger, Walgreens spokesman, said in an email.

Ro said the pharmacies came to the attention of the DEA based on several red flags, primarily the volume being shipped to these outlets.

The inspection warrants will allow the DEA’s diversion investigators to examine the pharmacies’ records and receipts to determine whether drugs were being diverted to the illicit market.

The pharmacies are not required to stop selling controlled substances, which include narcotic painkillers, while the DEA conducts its inspection.

The DEA has been ratcheting up its focus on drug wholesalers and pharmacies in recent months as it attempts to battle what the Centers for Disease Control and Prevention call a prescription drug abuse “epidemic.” Deaths from narcotic painkillers now exceed those of heroin and cocaine combined.

Florida has long been considered the epicenter of prescription drug abuse and the DEA has, over the past year, dismantled dozens of “pill mills” – sham pain clinics whose doctors write prescriptions for thousands of pain pills to drug dealers and addicts.