Gardaí were last night questioning a man in relation to the seizure of heroin worth an estimated €4 million on the outskirts of Dublin city yesterday.
It is believed the drugs were brought into the State in the past week, probably from Afghanistan via Spain.
The haul brings to more than €25 million the value of heroin seized in the State this year. This is almost four times higher than the €6.4 million seized last year.
The 17kg of heroin found yesterday were in a hold-all bag in a car being driven by a 23-year-old Dublin man when it was stopped near Rathcoole, Co Dublin, at 12.30pm. Officers from the Garda National Drugs Unit had the car under surveillance before stopping it and finding the drugs.
The arrested man was taken to Clondalkin Garda station where he can be held for up to seven days without charge. A number of follow-up searches were being carried out last night.
At the suspect's home address in the western part of Dublin city centre, gardaí found a smaller quantity of what they believe to be heroin.
All of the drugs seized had last night been taken for forensic analysis. The origins of the car being driven by the arrested man was also being checked by gardaí.
The drugs were owned by a major west Dublin drug dealer.
Senior gardaí have become increasingly concerned in recent months at the amount of heroin being seized.
They say heroin is now so readily available, even in rural areas, that two of the biggest seizures to date of the drug here in recent months had no impact on its availability or price on the street.