British Prime Minister Theresa May yesterday pleaded for an urgent deal with the European Union on post-Brexit security cooperation, warning that citizens' lives were at stake.

In a speech at the Munich Security Conference, she acknowledged that no deal currently exists between the EU and a third country "that captures the full depth and breadth of our existing relationship".

But she said there was no reason both sides could not come up with practical ways to create a "deep and special partnership" on security.

"We cannot delay discussions on this," May said.

She also warned European partners not to put politics above cooperation against crime and terrorism.

"This cannot be a time when any of us allow competition between partners, rigid institutional restrictions or deep-seated ideology to inhibit our cooperation and jeopardise the security of our citizens," May told an audience that included European Commission chief Jean-Claude Juncker.

The premier warned that if there was no deal on security by the time Britain leaves the bloc in March 2019, speedy extraditions under the European Arrest Warrant "would cease".

And if the UK were no longer part of Europol, the EU's law enforcement agency, information sharing would be hampered -- undermining the fight against terrorism, organised crime and cyberattacks.

"This would damage us both and put all our citizens at greater risk," May warned, urging European leaders to show "some real creativity and ambition" in coming up with a bespoke UK-EU security pact.

Some experts have warned that cooperation on police and security matters could be limited by Britain's refusal to accept the jurisdiction of the European Court of Justice (ECJ) after Brexit.

May appeared to respond to those concerns by saying that the UK would "respect the remit" of the ECJ when working with EU agencies, in return for "respect for our unique status as a third country".