A group of Indian-origin men, including a father-son duo, have been convicted of running what Scotland Yard described as a large-scale fake pharmaceuticals drugs factory in west London.

The Metropolitan Police said its Cyber Crime Unit led an investigation after it received intelligence from the Drug Enforcement Administration (DEA) in the US that the men were selling pharmaceutical drugs on the dark web.

Allen Valentine, his son Roshan Valentine, and Roshan's childhood friend Krunal Patel were found to be producing and selling Benzodiazepines, a type of sedative which is a Class C controlled drug.

The police said they made at least GBP 3.5 million in illicit profit with this operation. The trio also had several accounts on different dark web markets and advertised the sale of Xanax, Diazepam and in the past Valium.

"The three men ran a sophisticated, large-scale production of fake pharmaceutical drugs sold on the dark web that appeared to be genuine," said Detective Constable Alex Hawkins, of the Met Police's Cyber Crime Unit, who led the investigation.

"Their operation was solely for the greed of those involved bearing no concern for the vulnerabilities of those purchasing these drugs. Some of the drugs contained completely different chemicals from those which should be in the genuine tablets; some of them are extremely dangerous," he said.

Hawkins said the investigation led to the first seizure of these chemicals in the UK and legislation will be amended later this year to include these drugs under the Misuse of Drugs Act as Class A banned substances.

"Stopping the manufacturing of these drugs has removed a significant risk to the public. We would like to thank pharmaceutical companies Viatris and Teva UK for assisting the Met in our investigation and supporting our prosecution against these dangerous and fraudulent men," he added.

"I'd urge anyone to seek medical advice and obtain a prescription for medication through a doctor. If you buy from the dark web there is no guarantee what is in the substances, as with this case." All three men were charged with conspiracy to produce Class C drugs and money laundering offences in August last year.

Krunal Patel, 40, and Roshan Valentine, 39, went on to plead guilty at Isleworth Crown Court earlier this year while Allen Valentine, 62, pleaded not guilty to the drugs offences and was found guilty this week following a trial at the same court.

Their charges include conspiracy to produce, possess and supply controlled drugs of Class C, possessing a controlled drug of Class C with intent to supply; conspiracy to sell trademarked goods without authorisation, conspiracy to use a registered trademark for labelling or packaging goods without authorisation, possession of articles designed to make unauthorised copies of registered trademarks, and conspiracy to conceal, convert or transfer criminal property.

All three will be sentenced at a later date and a confiscation hearing to legally obtain their illegal profits will take place in due course.

"Our specialist Cyber Crime Unit are experts at infiltrating the sale of illegal items on the dark web. We work collaboratively with International Law Enforcement partners to ensure operations like this are stopped in their tracks," said Detective Superintendent Helen Rance, who leads the Met Police Cyber Crime Unit.

The unit's detectives began the investigation in January 2022 and, soon after, they discovered the three men were visiting a warehouse unit at Acton Business Park in west London.

It was from here that the drugs were produced, packaged and supplied. The men were operating under the guise of a company called Puzzle Logistics Limited which was formed in 2016, the Met Police said.

Each of the men visited the unit on a daily basis, often staying for much of the day. Krunal Patel would frequently leave with large bags, returning 10 to 15 minutes later without the contents of the bags.

Users would purchase the drugs on the dark web, paying in cryptocurrency, which was then posted.

The Met's Cyber Crime Unit said it has detailed knowledge of the dark web and training in cryptocurrency, allowing them to efficiently progress the investigation.

Detectives utilised specialist cyber tactics to prove it was the Valentines and Patel who were making and selling the illegal substances.

They determined the three men converted GBP 3.5 million from cryptocurrency into fiat currency or pound sterling, and the accounts were frozen by police.

On August 17, 2022, Krunal Patel was arrested near the warehouse, with 15 parcels labelled for posting to addresses across the UK.

Inside those parcels were tablets imprinted "Xanax" and "Teva", both brand names for licensed medicines within the Benzodiazepine group. Roshan and Allen Valentine were arrested later that same day.

Officers searched the warehouse and found a concealed laboratory where a large amount of equipment and several containers of chemical substances were discovered, along with numerous crates of pills manufactured on site.

The pills were analysed and found to contain Class C drugs from the Benzodiazepine group including Deschloroetizolam, Flubromazepam, Bromazolam and Flualprazolam.

The Met Police said its enquiries are currently ongoing to verify claims made by Allen Valentine to the jury that he was a doctor with qualifications in pharmacy.