Two drugs seizures, one of heroin with a potential street value of €2 million and the other of cocaine, have resulted in the arrests of four people.
Gardaí seized the large quantities of drugs in Clondalkin and Swords in Dublin on Saturday.
The four people were still being detained last night.
At 9.30pm on Saturday, gardaí stopped and searched a car at Cherrywood Crescent, Clondalkin.
A large quantity of heroin, approximately 10kg, was found in the vehicle.
Gardaí said that depending on the results of forensic analysis of the substances seized, the heroin might have a potential street value of up to €2 million.
A quantity of cash which was found in the car was also seized by gardaí.
A man and woman who were in the car when it was stopped were arrested and are now detained under section 2 of the Criminal Justice (Drug Trafficking) Act, 1996.
Under the Act they can be held for up to seven days.
A third person, a woman, was arrested at a house in Kilcronan Grove, Clondalkin, in follow-up investigations.
All three are detained at Ronanstown and Clondalkin Garda stations.
The operation was co-ordinated by gardaí from the National Bureau of Criminal investigation.
In the second raid, gardaí from the drugs unit at Coolock Garda station stopped and searched a car on the M1 motorway at Swords at about 10.10pm on Saturday.
During that search, 4kg of a substance, which was believed to have been cocaine, was discovered.
It has an estimated street value of €320,000.
The driver of the car, a 47- year-old man with an address in England, was arrested and is now being detained at Coolock Garda station.
He was held under the Drug Trafficking Act.