Britain and the EU should sign a new security treaty and must not let ideological differences block co-operation in that sector after Brexit, Prime Minister Theresa May said on Saturday.
May said key aspects of a future partnership should be effective from 2019, emphasising she was unconditionally committed to European security. Britain is due to leave the European Union in March of next year.
Speaking at a Security Conference in Munich, she said Britain would respect the role of the European Court of Justice (ECJ) with regard to certain security agencies, but would not be subject to its jurisdiction.
"We must do whatever is most practical and pragmatic in ensuring our collective security," she said.
"This cannot be a time when any of us allow competition between partners, rigid institutional restrictions or deep-seated ideology to inhibit our co-operation and jeopardise the security of our citizens."
May argued that leaving the ECJ's jurisdiction should not make it harder to extradite terrorism suspects or share information.
Britain says that the issue of security is too important to become entangled in the minutiae of Brexit negotiations, something that European Commission chief Jean-Claude Juncker also said on Saturday.
He told the conference that the EU and Britain should resolve security questions separately to other Brexit issues such as trade.
Britain's interior minister last year told the EU it could "take our information with us" if it left the bloc without a deal on security, jeopardizing its membership of agencies such as Europol.
A government's policy paper on security acknowledged a new form of agreement was needed because there was no clear precedent for security co-operation between the EU and other states.
"I recognize there is no existing security agreement between the EU and a third country that captures the full depth and breadth of our existing relationship," May said, though there were precedents for strategic relationships between the EU and other countries in other areas.
"There is no legal or operational reason why such an agreement could not be reached in the area of internal security," she said.