National Crime Agency (NCA) officers arrested six of the group at addresses across Merseyside as well as a 47-year-old man in Dumbarton on suspicion to supply heroin - and the eighth was produced from prison.
Analysis of messages acquired as part of Operation Venetic – an investigation into the encrypted messaging platform EncroChat – led to today’s arrests.
Officers believe the suspects were planning to produce large quantities of amphetamine at a location in Scotland, as well as trafficking heroin from Scotland to Merseyside.
The group, aged between 34 and 66, remain in custody.
On 4 December 2020, as part of the same investigation, more than 620kg of APAA - a substance used in the manufacture of amphetamine - was seized and two men arrested after arriving on a flight from Turkey.
Both were later released under investigation.
Ian McConnell, NCA operations manager, said: “Producing amphetamine on an industrial scale would have devastating consequences for the community - drug trafficking thrives on inciting violence, spreading fear and exploiting vulnerable children and adults for criminal gain.
“Today’s action has led to the arrest of eight suspected members of an organised crime group and will continue to target those at the top of the drug market chain, to make their businesses unviable and keep people safe.”