Giving evidence to Westminster’s Northern Ireland affairs committee, chief constable Simon Byrne said it would take much longer to process extradition requests governed by the European Convention on Extradition.

He said: “It is imagining a world where you are going from Wi-Fi to a modem. You will still have connectivity but it will take a lot longer.”

However, Mr Byrne said there is “a tacit acceptance if we end up in a no-deal scenario that then, in the context of Ireland, we could press forward with trying to negotiate bilateral agreements quickly”.

He said his counterpart south of the border, Garda Commissioner Drew Harris, had not given him any commitments but there was already a “framework” for cross-border collaboration.