More than €8 million worth of drugs have been seized as part of a joint investigation between gardaí and Polish police.
Thirteen Polish nationals based in Ireland were arrested as part of the investigation targeting transnational organised crime.
The investigation targeted a network of Polish criminal organisations with "leadership, transport and distribution cells based in Poland, Spain and Ireland", gardaí said.
The drugs seized in Ireland included 340kg of cannabis herb, 155kg of cannabis resin and 26kg of amphetamines, as well as over €800,000 in cash.
In total, over 800kg of controlled drugs along with seven firearms and several hundred rounds of ammunition were seized across a number of European countries.
Police across several European countries were involved in the investigation coordinated by Eurojust and supported by Europol.
The gangs were identified to be coordinating the importation of cannabis into Ireland and other European countries.
A number of the prosecution cases in Ireland were transferred to Poland for prosecution.
Charges have been filed against 170 individuals in Poland by the District Prosecutors Office in Gliwice and assets worth over €11 million have been seized by Polish investigators across Europe as being the proceeds of crime.
Detective Superintendent Dave Gallagher of the Garda National Drugs and Organised Crime Bureau said the investigation shows the "international dimensions of transnational crime and demonstrates fully the benefits of our ongoing collaboration with law enforcement in other jurisdictions".
He said these investigations continue to "disrupt, prosecute and dismantle transnational criminal organisations".
