Derek Dragsnes, 49, a labourer, of Glasgow, ran the unit in the Lanarkshire village of Salsburgh.

He was sentenced at the High Court in Livingston after pleading guilty at a hearing last month at the High Court in Edinburgh with being concerned in the supply of etizolam.

The offence was aggravated by the accused’s connections to serious organised crime.

Prosecutors told the court how a lengthy and detailed police search of the premises on Springfield Road uncovered pill manufacturing equipment spread out over six rooms. One room contained a pill press machine capable of producing 171,000 tablets per hour. In another room, officers seized 53.3kg of white powder containing etizolam, which is known as street valium.

This quantity alone would have produced more than 300,000 tablets with an estimated street value of £165,600.

The court also heard that a total of 177,731 tablets of five different designs containing etizolam with an estimated value of £88,800 were recovered during the police search.

David Green, procurator fiscal for homicide and major crime, said: “This was a coordinated effort to detect significant quantities of illegal and harmful drugs. This individual is now serving a lengthy prison sentence. The Crown, working with the police, painstakingly built a case to disrupt a network of drug supply.

“With each case of this kind, we can help reduce the harm that these drugs inflict on Scotland’s communities.

“We are targeting all people who threaten communities across Scotland, not only drug manufacturers but also those who direct their movements. With each case of this kind, we can help reduce the harm these drugs inflict on those communities.”