In a police sting in Spain and Britain six people have been arrested, suspected of importing and selling mass amount of fake medication from Asia including Viagra, Europol said on Monday.
"The members of the criminal gang were importing fake pharmaceuticals from Asia -- mainly China and Singapore -- and distributing them via the Internet to 'customers' throughout Europe," the police agency said in a statement.
Police seized some 300,000 doses of fake medicine after an operation by Spanish police in the southeastern city of Murcia as well as in Britain and the Mediterranean island of Cyprus, Europol said.
Anti-potency pills like Viagra and Cialis as well as generic drugs were distributed by the group, it added, saying the drugs were made in clandestine laboratories.
One Spanish, two Romanians and a Dutch citizen were arrested in Spain, while the two Britons were arrested in their home country on Wednesday and Thursday, said Europol.
"They were the most important individuals in the network, but other arrests could follow," Europol spokesman Soren Pedersen told AFP.
"Unlicensed, untested and potentially laced with dangerous filler ingredients, fake medicine can put users' health and even life at risk," Europol added.
The World Health Organisation said half the medication sold on the Internet was fake.
In September last year, police and customs officers from 81 countries in an operation seized a record 2.4 million doses of counterfeit medicines to be sold on the Internet.
They arrested 55 people in 10 countries mainly in Europe, Japan, Colombia and Uruguay.