Chinese women are being trafficked into Ireland to work on cannabis farms. They are alongside other illegal Chinese and Vietnamese who have arrived here through Europe. Six Chinese were caught at Dublin Airport, without documentation, apparently having flown in from Spain last week.
The Chinese-run cannabis factories spread from England, through Scotland and into Northern Ireland before being established in the Republic.
Gardai were urged to review investigations of trafficking after a Chinese woman spent 15 months in jail on drug charges.
She claimed to have been a victim of forced labour and that she escaped from a cannabis factory in the West of Ireland.
The Migrant Rights Centre said she was trafficked through England and forced to tend cannabis plants with a street value of €125,000.
She was wandering barefoot, bleeding and suffering from hypothermia when she was found in a remote location.
But Irish criminals have realised the potential of the farms and have established their own operations.
In February, a garda search in Co Wicklow unveiled a cannabis farm near Donard with 400 plants worth an estimated €250,000. They also found a heating and irrigation system.
The find was uncovered when Customs officials found the cannabis as officers carried out routine fuel sampling.
Operation Nitrogen is aimed at finding the cannabis growing houses. Drug officers have located cannabis factories this year in Meath, Galway and Donegal and seized plants with an estimated street value of €760,000.
In the past three years, cannabis factories have been detected in houses, many along the border, set up by Asian gangs.
The Chinese gangs were previously targeted in a series of operations by the London Metropolitan Police and other agencies in Britain. They were forced to move first to Scotland then to Northern Ireland and then here.
Irish gangs set up as gardai began dismantling the Chinese factories to cash in on the rise in popularity of herbal cannabis.
Two weeks ago, detectives from the PSNI's Organised Crime Branch rescued a Chinese teen and arrested two men over a cannabis farm outside Belfast.
The arrests were part of an operation, which has been running in the North since September 2009 which seen the closure of many cannabis factories and the seizure of cannabis with a street value of £2.2m.
By Charlie Mallon