About 5,000 cannabis plants worth an estimated 1.5 million euro have been seized in one of the biggest drugs busts of its kind.
A warehouse on a rural industrial centre in the Midlands which had been converted into a massive grow house operation was raided on Tuesday night.
The unit at Aughnacarna, a few miles north of Tullamore, Co Offaly, was split into 10 compartments, complete with individual water filtration systems, high powered lighting and air conditioning.
Garda sources revealed eight of the sealed rooms were full of plants and operations in a ninth room had been dismantled with plants ready for packing and distribution. A tenth room, also designed for cultivation of the drug, had been cleared out.
The cannabis factory is believed to be about five to 10 times the size of the average grow house operations frequently broken up in rural homes and cottages by gardai over the last few years. The warehouse had also been kitted out with living quarters.
Three men, two in their 20s and one in his 30s and all from Asia, were detained during the raid near Durrow at 9.30pm. The suspects were detained under section two of the Criminal Justice (Drug Trafficking) Act at Tullamore Garda station, Co Offaly. The men were said to have been living in the warehouse.
The unit is believed to be the single biggest grow house operation uncovered by gardai and one of the most sophisticated. Doors and windows in the unit, including roof skylights, had been sealed.
High powered lights were still burning throughout the warehouse as the drugs squad and local officers stripped the rooms and bagged plants for destruction.
Irish grown cannabis is now regarded as the fastest growing problem drug with the modern cultivation techniques able to turn out high-strength fresh crops of the drug every four months.
Cannabis surpassed cocaine and heroin in 2010 as the most common problem drug among new cases on treatment programmes, according to the Health Research Board.