Gardaí from the Garda National Drugs Unit and members of the local drugs unit from Clondalkin and Ballyfermot have arrested three men in the Waterstone Park area of Palmerstown as part of an ongoing operation.
The three men aged 32, 35 and 50, are being detained under section 2 of the Criminal Justice Drug Trafficking Act, 1996 at Clondalkin and Ballyfermot garda stations.
Gardaí also seized up to six kilos of heroin with an estimated street value of up to €1.2 million.
Investigations are continuing.