Four men were being questioned today after gardai seized drugs suspected to be heroin with a street value of €1.2m.
Drug squad officers and detectives searched four cars in Palmerstown, Co Dublin, and seized the 6kg haul.
The vehicles were stopped on the Kennelsfort Road in the south Dublin town shortly after 9pm last night.
The men, all aged in their 20s, were arrested and are being held at Clondalkin and Ballyfermot garda stations under Section 2 of the Criminal Justice Act. They can be detained for up to seven days.
Gardaí said the operation, involving officers from the Organised Crime Unit, the National Drug Unit, the National Bureau of Criminal Investigation and local units, resulted from continuing intelligence.
The drugs will be analysed by the Garda Technical Bureau later today.