Gardai discovered a massive 'chop shop' where high-end stolen cars were being cut up and re-painted as part of an elaborate scam.
Officers raided two locations in Tallaght where they made the discovery yesterday morning.
Sources have revealed that one Audi worth €70,000 was being "worked on" when officers stormed the business.
A large number of gardai swooped on the two premises and immediately took control of the garages and set to work seeking documentation and computer records.
Several garda vehicles could be seen at the site, blocking the exit and keeping the site contained.
The searches took a number of hours to complete and were still ongoing last night.
A number of stolen vehicles had been found in the garages and have been seized by gardai.
Plain clothes detectives and uniformed officers, numbering more than a dozen, could be seen walking in and out of the garages. Gardai were also placed on the reception doors of each garage to stop members of the public and customers gaining entry.
Yesterday's raid was a joint operation between the traffic corps and Tallaght gardai.
A senior source told the Herald last night that gardai have been monitoring the garages for a number of weeks.
"What is happening is that the criminals involved in this enterprise have been taking possession of wrecked cars in the UK and bringing the chassis over here," the source said.
"Gangs involved in car theft here then steal a car which matches the model of the chassis that belongs to the car brought from the UK. The cars are then fitted up to look like the genuine article.
"When this raid happened, gardai discovered a number of engines and bits of cars in the premises."
It can also be disclosed that many genuine customers have been using the raided garages for services and repairs but were completely unaware of the illegal activity that was taking place there.
Local workers said the raid squad arrived around mid-morning when the businesses were open.
"Nobody really knows what is going on," said one.
"It looks like something big and the gardai have been checking the details of all the cars on the premises."
The vast majority of the people working in the two raided garages are Eastern European.
Sources said that a major Crumlin criminal is suspected of supplying many of the stolen cars for the Tallaght garages.
Gardai revealed this week that approximately 6,500 cars are stolen a year, and about 60pc of those do get recovered.
However, 40pc of those cars end up going missing, or they could end up being used for stolen parts, or exported abroad.