Theresa May has called for a new security treaty with the EU after Brexit, warning against “deep-seated ideology” from Brussels scuppering a deal.
The Prime Minister said both sides had to do “whatever is most practical and pragmatic” to protect citizens.
She was speaking at the annual Munich security conference in Germany in a bid to convince world leaders that Britain is not retreating from the global stage.
Mrs May put the success of past security cooperation at the heart of her speech on Saturday, praising cooperation between UK and EU agencies in thwarting deadly terror attacks.
“Europe’s security is our security,” she said. “And that is why I have said that the UK is unconditionally committed to maintaining it.”
But the PM had stronger words for EU officials on a future security deal after the transition period ends – expected to be at the end of 2020.
“We have never defined our foreign policy by our membership of the EU,” she said.
“If the priority in the negotiations becomes avoiding any kind of new cooperation, then this political doctrine and ideology will have damaging real-world consequences for the security of all our people.
“As leaders, we cannot let that happen”
“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.
“We must do whatever is most practical and pragmatic in ensuring our collective security.”
She was tackled in a question by Wolfgang Ischinger, former German ambassador to the UK and US.
He said “things would be much easier without Brexit”, to applause from the hall.
Mrs May responded by insisting the UK would be leaving and “there will not be a second referendum or anything like that”.
Jean-Claude Juncker, the European Commission President, responded after her speech that the EU needed to resolve security issues separately from Brexit.
“I do not want to mix up security policy considerations with other considerations,” he said.
Mrs May was praised afterwards by backbench MP and former Army captain Johnny Mercer, who has previously criticised the Government for not spending enough on defence.
He told Sky News the PM was “absolutely right” and that “now we need to move on to this treaty”.
“Talking hardball around security” is necessary, he added. “But I’m afraid that is in the interests of the British people.
“Let’s stop getting upset about this vote, as they very much are around the bars here.”
However, Alison McGovern, an MP who is a supporter of the anti-Brexit group Open Britain, said: “Theresa May just made an extremely persuasive argument against Brexit.”
As part of her trip to Germany, Mrs May held talks with Angela Merkel in Berlin on Friday.