Drugs worth €1m have been seized after searches were carried out in Dublin and Meath.
7kg of heroin was found and three men in their 40s and 50s have been arrested.
The joint operation was carried out this morning by the Garda National Drugs and Organised Crime Bureau and the UK National Crime Agency.
The three are being held at Dublin Garda stations.
Investigations are ongoing, nationally and internationally.
Assistant Commissioner John O’Driscoll of Special Crime Operations said in a statement: "This seizure of a large amount of heroin is the result of an intelligence-led investigation.
"This demonstrates the increased capabilities of the Garda Síochána when working with our international partners to keep people safe and to target those who would attack our communities with drugs.”
Detective Chief Superintendent Angela Willis of the Garda National Drugs and Organised Crime Bureau added: "This substantial seizure of heroin will help keep our communities and people safe and will impact significantly on organised crime groups involved in the international drugs trade."