Gardai are warning the public not to sell cars to ready-cash dealers as the vehicles are often used for criminal activity before being illegally dumped.
The warning comes after the Garda Stolen Motor Vehicle Investigation Unit (SMVIU) and the armed support unit were involved in an operation against gangs that offer cash for older registration models.
As part of last Thursday's operation in Dunsink Lane, Finglas, more than 200 vehicles suspected of being dumped by one gang were removed by Fingal County Council's waste enforcement division.
Gardai and the council were backed up by Customs, the Department of Social Protection and the Waste Enforcement Regional Lead Authority.
"The criminal activities of those who continue to be involved in buying and selling cars this way continue to be a source of major concern for gardai, and the public should not engage with them in any way," a senior source said last night.
"This is an organised criminal gang based primarily in Finglas and Ballymun but also in Co Meath.
"Gardai have found that they regularly have signs up near NCT centres, and if someone has failed their NCT on a car that is, for example, over 16 years old and has multiple problems, it is tempting for the person to take €500 or so to get rid of the vehicle.
"But investigations have established that these cars are often then used for crimes such as burglaries, robberies, the movement of drugs around the city and drive-offs from petrol stations.
"Because the vehicles are not re-registered, it makes it very difficult for gardai to trace who was driving the car.
"All gardai can do is go back to the original owner who has sold the car, but inevitably they know nothing about who bought it off them.
"People should only use leg- itimate authorised recycling businesses if they need to get rid of their old cars, but the problem is that they won't get as much money for them."
The Herald has also learned that the mob targeted in last week's operation is suspected of being behind a spate of organised thefts of high-end 4x4 vehicles in north Co Dublin and Co Meath in recent weeks.
"You are talking about at least three a week over the past month. It is starting to become a worrying trend," the source added.
In 2017, illegal cars-for-cash posters effectively disappeared from Dublin city and county after gardai smashed the sophisticated criminal operation behind them under an investigation called Operation Sign-Off, but NCT centres are now being targeted by the gang.
Fingal County Council has revealed that up to 80 personnel worked on last week's operation in Dunsink Lane.
"With support from contractors, recovery operators and vehicles assessors, a total of 200 end-of-life vehicles were removed off-site and brought to authorised treatment facilities for recycling and disposal," a spokesperson said.
"As part of the operation, 140 tonnes of illegally dumped waste was also removed.
"Investigations are ongoing, and if sufficient evidence is obtained, fines will be issued and prosecutions initiated under the Waste Management Act 1996 and the Litter Pollution Act 1997 as amended.
"For the 200 scrap cars that were found illegally dumped, fines will be issued to the registered owners."
Fingal mayor David Healy said: "This was a necessary operation to dismantle an un- authorised and environmentally harmful activity."