The raids across the West Midlands, Greater Manchester, Staffordshire and Merseyside follow a lengthy intelligence-led investigation, codenamed ‘Operation Subaru', by the MHRA's Criminal Enforcement Unit.

In searches of 22 residential and commercial premises, hundreds of thousands of doses of medicines have been seized, including controlled drugs such as opioid painkillers and anti-anxiety medicines, around £100,000 in cash, luxury watches and suspected criminal assets held in cryptocurrency. The MHRA has also obtained restraint orders for more than £3.5m in assets suspected to be linked to criminal activity.

Andy Morling, head of the MHRA's Criminal Enforcement Unit, said: ‘Operation Subaru is the largest investigation we've ever undertaken and demonstrates the MHRA's commitment to protecting the public by dismantling the organised international criminal networks that cause so much harm.

‘Trafficking in medicines destroys lives and places a huge financial burden on wider society. Our dedicated team will stop at nothing to tackle this illegal trade by taking potentially harmful medicines off the street and bringing those responsible to justice. As today's operation shows, there is nowhere to hide.'

The suspects are being held for questioning.