Police swooped on a number of addresses across the UK this morning, seizing what are believed to be fake and illegal drugs and making several arrests, as part of a concerted campaign against medicine counterfeiters.

Four people in London and one in West Yorkshire were arrested as a result of the raids, which uncovered caches of drugs estimated to be worth several hundred thousand pounds. The swoop came after investigations by the UK’s Medicines and Healthcare products Regulatory Agency (MHRA).

The MHRA probe comes as the European Commission issued a new warning against the rise of fake drugs being sold through the internet, with 170 counterfeit medicines identified in illegal distribution channels over the past five years in the European Union Member States. In fact, the World Health Organisation estimates that 8% to 10% of the global medicine supply chain is counterfeit, reaching as high as 25% in some countries.

A spokesman for the MHRA said that while it is virtually impossible to get a sense of how widespread the trade in counterfeit medicines over the Internet and other channels is, consumers can be encouraged that the UK has only seen a handful of case of fake drugs getting into the legitimate supply chain over the last few decades.

The most recent case, which occurred about a year ago, concerned fake batches of Pfizer’s cholesterol-lowering drug Lipitor (atorvastatin), which necessitated a recall of the medicine.

Mick Deats, head of Enforcement & Intelligence at the MHRA, said: "Individuals or organisations who attempt to supply counterfeit medicines can expect to be thoroughly investigated. Where appropriate they can be prosecuted by the MHRA using a variety of legislation which could result in up to 10 years imprisonment and substantial fines."