Brexit will not negatively affect cooperation between the intelligence services in Europe, the EU's anti-terrorism coordinator said.
"The exchange of information is not impacted," Gilles de Kerchove said on the sidelines of a meeting of EU interior ministers in Zagreb on Friday.
Cooperation between the intelligence services is already "outside the institutional framework of the" EU, and non-members Norway and Switzerland are already part of it, he told AFP.
Britain will also be represented within this framework after it leaves the European Union on January 31.
He said that the issue is more whether if, and in what form, London will continue to have access to EU police data.
Britain shares intelligence through the Schengen Information System (SIS) for law enforcement purposes, although it is not part of the passport-free Schengen zone.
In recent years, the SIS information base has become an important tool for tracking jihadists entering Europe from Syria and Iraq.
De Kerchove was not able to say how the EU could continue to cooperate with Britain in regard to the SIS.
But "it is impossible for a non-EU member to have the (same) degree of intimacy as that of an EU member."
The question should be resolved in talks between London and Brussels on their future relationship, expected to begin in February.
De Kerchove said the EU has worked in close cooperation with the US on law enforcement matters and "it would be absurd that our geographically close neighbour finds itself in an inferior situation to that of the Americans, particularly in the fight against terrorism."
The Belgian EU official also expressed concern over the situation in Iraq and Syria.
He said recent developments on the ground could lead the Islamic State group to "rebuild" after the defeat of its caliphate.
A pullout of US troops "would certainly weaken the capacity of the Iraqi army to fight what remains of" the IS.
He also said the fate of some 5,500 IS fighters has not been sufficiently clarified.
"A good number" of them have already returned home, around 600 are in prisons in the region and at least one quarter are dead.
But the number of dead is probably higher as many jihadists have been killed in battles for the caliphate but authorities have not received confirmation.