Fake versions of rimonabant, an anti-obesity drug are being sold on the Internet. Plus, the drug has not been approved for sale in the European Union, the European Commission warned consumers on Monday.

Fakes of the drug rimonabant, an experimental drug from Sanofi-Aventis, which is still being tested by the European Medicines Evaluation Agency, are being sold on several Web sites under the proposed brand name of Acomplia, the EU executive said.

“Patients who buy unlicensed and counterfeit or illicit copies of rimonabant may be putting their health at risk,” the Commission said in a statement.

EU member states have identified 170 medicines as being counterfeit and illegally sold over the past five years, particularly Viagra and Cialis to treat erectile dysfunction, and Tamiflu for viral infections.

U.S. drug firm Pfizer welcomed the Commission’s warning.

“Pfizer is very concerned about the surge in counterfeit medicines, putting at risk the lives and well-being of patients in Europe and elsewhere,” said Julian Mount, senior director of European trade at Pfizer.

“However, illegal Internet trade is just one part of the story. Counterfeits have also made it into the legitimate medicines supply chain in Europe,” Mount said.