The U.S. Food and Drug Administration advised consumers Wednesday not to purchase several prescription drugs from a Manitoba online pharmacy, allegations one of the site's operator's said were baseless and politically motivated.

The FDA warned against prescriptions ordered through a list of 10 websites including rxnorth.com and canadiandrugstore.com. Those orders are filled via Mediplan Prescription Plus Pharmacy or Mediplan Global Health of Minnedosa, Man.

The news release claimed that preliminary lab results of drugs intercepted through the provider found counterfeit versions of Lipitor, Diovan, Actonel, Nexium, Hyzaar, Ezetrol (Zetia), Crestor, Celebrex, Arimidex and Propecia.

Andy Troszok, an online pharmacist and past-president of the Canadian International Pharmacy Association, said the FDA hasn't presented any information to back those claims.

"They have not shown any evidence in that report that the accusations have validity," said Troszok. "Our organization is asking for clarification on this issue before we make any generalized statements."

Troszok questioned how the FDA defined "counterfeit," saying there are allowable variances in active ingredients from batch to batch from brand-name manufacturers, and also when comparing generics and brand names.

Andrew Strempler of Mediplan said the FDA warning is the latest tactic designed to prevent uninsured Americans from getting their drugs from outside of the U.S.

"U.S. drug companies, along with the FDA, are really starting to target companies like ours," said Strempler. "These allegations are completely false."

Strempler added his company regularly tests the drugs it sells and they are safe and reliable.

The FDA said in its statement that many of the drugs were being shipped from other destinations. It cited a 2005 seizure where it claimed 85 per cent of drugs promoted as Canadian actually came from 27 other countries.

In addition to pressure from the U.S. government, the performance of the Canadian dollar has driven many internet pharmacists to get their drugs from overseas suppliers.

Health Canada spokesman Paul Duchesne said the department is investigating.

"If there are any safety concerns we will be sure to alert the public," said Duchesne.

Importing drugs into the United States is illegal, though the FDA generally does not stop small shipments purchased for personal use.

With files from the Canadian Press and the Associated Press