Spanish police said Tuesday they have detained 13 people suspected of selling large quantities of fake medication, including erectile dysfunction drugs and antibiotics, made in Asia over the Internet.
The authorities seized nearly 420,000 fake pills during a search of 136 packages found in airmail and luggage in Spanish airports, police said in a statement.
The fake medication included contraceptives, weight loss pills, vitamins, steroids, pain killers and Viagra, the statement added.
The vast majority of the pills were made in China and India, but police also seized counterfeit medication from Malaysia, Colombia, Paraguay and the United States.
Police gave no estimate for the value of the pills.
"The main goal of the operation is to raise public awareness of the risks that buying medicine from irregular sources entails," police said in the statement.
Spanish police gave international law enforcement agency Interpol the web addresses of 113 Internet sites that illegally distributed medicine.
According to the European Alliance for Access to Safe Medicines, 62 percent of drugs bought on the Internet in 2011 were fake.
The Center for Medicine in the Public Interest, a US non-profit medical research group, estimates the traffic in fake medicine generated 55 billion euros ($75 billion) globally in 2010, up 90 percent from 2005.
In Europe, meanwhile, a study conducted by pharmaceutical giant Pfizer in 2010 showed that the market for fake drugs was worth around 10.5 billion euros.