Four Irish people are expected to face charges in the coming days after an anti-drugs police team raided a rented house in Rotterdam late on Friday night.
The operation was part of a European crackdown on drugs smuggling.
Dutch police have confirmed that the four are expected to appear before an examining magistrate on charges of possessing substantial quantities of drugs and weapons.
"Weapons and drugs were found at the scene, and arrests of drugs suspects were made," a police report issued in Rotterdam yesterday stated. The names of those being held have not been released.
Dutch police sources said one of the men is suspected of organising shipments of heroin and cocaine out of Rotterdam.
The arrests followed a series of planned searches leading to the gang's hideout house, rented by a Dutch associate.
All that the Dutch authorities would reveal last night was that four arrests had been made. Two Irish men and two Irish women who were arrested late on Friday night with help from Garda observers as a result of an ongoing international anti-drugs operation, are expected to be held in custody to appear before an examining magistrate within the next two days. According to a spokesman at least four weapons and a substantial quantity of drugs were found.
The arrests were connected to the seizure of heroin worth €11 million, ammunition and a sub-machine gun in Dublin last Tuesday.