A senior detective has warned that policing faces a real challenge if quick and effective extradition laws are lost in the wake of Brexit.
Detective Chief Superintendent Hugh Hume told politicians in Stormont that negotiations on the split with Europe needed to protect a modern approach to the transfer of criminal and terror suspects.
Mr Hume told the Justice Committee: "The loss of the European Arrest Warrant would be one of the main concerns that we would have."
The senior detective said that the UK made its second highest number of extradition requests to the Republic of Ireland.
"On the world stage Ireland is an important extradition treaty for the United Kingdom," he said.
"It's not just Northern Ireland. It's important to note it's the United Kingdom."
Mr Hume said the extradition issue with the Republic would be at the top of the list in Brexit talks involving British justice officials.
The detective joined Department of Justice officials at the committee as politicians explored the security, customs and policing issues that might arise in the wake of Brexit and how the border between the Republic and Northern Ireland would be affected.
Mr Hume also said it was too early to run a threat assessment on dissident terrorist activity or border security issues that Brexit may create.
"Until we really know what it's going to look like it'd be pre-emptive to start thinking about a threat assessment around the border," he said.
"At this stage it would all be aspirational.
"It's just too far off at the moment."
David Lavery, Department of Justice official, told the committee that there was ongoing dialogue with officials in the Republic on the potential for Irish ports and airports to have UK immigration checks.
"There is an ongoing dialogue and it pre-dates Brexit between the UK and the Irish Republic about the movement of people," he told the committee.
