The PSNI has echoed concerns which have been voiced by police chiefs across the UK about the possible impact on law enforcement that a no-deal Brexit could have.
A national body warned that police could be powerless to arrest foreign crime suspects on the spot if Britain loses access to European databases and agreements.
In a statement released yesterday, PSNI Assistant Chief Constable Tim Mairs said: "The Chief Constable is on record - along with other Chief Constables across the UK - in expressing concern around the dilution of the European justice and home affairs measures, including for example, the European Arrest Warrant.
"From PSNI's perspective, these justice tools currently help support close collaboration with police partners right across Europe and in particular, our colleagues in An Garda Siochana with whom we work every day to keep people safe.
"While EU exit will not adversely affect the deep and embedded culture of collaboration between PSNI and An Garda Siochana, it is accepted that losing access to these tools will present us with challenges.
"While alternative arrangements will be available, they would be slower and more bureaucratic to operate."
ACC Mairs said that since the referendum, the PSNI has been part of a group convened by the National Police Chiefs' Council and the National Crime Agency which has been preparing for Brexit.
He said: "As part of this work, the PSNI's Extradition & International Mutual Assistance Unit is connected into the new International Crime Coordination Centre, which will work to ensure that PSNI, along with all other UK police services, are prepared and ready to use alternative arrangements should we lose access to the European justice and home affairs measures."