Video report by ITV News Security Editor Rohit Kachroo
Theresa May has told EU leaders that Brexit must not jeopardise European security, warning that "nothing must get in the way" of Britain and the EU "helping each other in every hour of every day to keep our people safe".
In a speech at a global security conference in Germany, the Prime Minister continued that leaders must do whatever it takes to ensure the security of Europe is protected after Brexit.
Mrs May called for a treaty protecting security cooperation between the UK and the EU, to allow them to respond swiftly to a world of rapidly evolving threats, and continued that if the bloc did not agree, there could be "damaging real world consequences".
Speaking to ITV News, Rob Wainwright, the Executive Director of Europol agreed with the Prime Minister that close collaboration between the EU and the UK would be essential for security post-Brexit.
Meanwhile on Friday, the heads of intelligence services in the UK, France and Germany gave an unprecedented warning to leaders not to meddle with intelligence sharing post-Brexit.
During her speech at the Munich Security Conference, the Prime Minister warned that "rigid institutional restrictions" and "deep-seated ideology" must not be allowed to jeopardise the safety of European citizens.
"The challenge for all of us today is finding the way to work together, through a deep and special partnership between the UK and the EU, to retain the co-operation that we have built and go further in meeting the evolving threats we face together," Mrs May said.
"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.
"We must do whatever is most practical and pragmatic in ensuring our collective security."
Watch Mrs May's speech in full
Mrs May wants the Supreme Court to have the final say over challenges to warrants issued in the UK.
She highlighted major cases where the UK and the rest of the EU have worked together to tackle terrorists and people smugglers and insisted it is in the interest of both sides to agree a strong security deal.
"To make this happen will require real political will on both sides," she said in her speech titled Road to Brexit: A Security Partnership.
"I recognise there is no existing security agreement between the EU and a third country that captures the full depth and breadth of our existing relationship.
"But there is precedent for comprehensive, strategic relationships between the EU and third countries in other fields, such as trade. And there is no legal or operational reason why such an agreement could not be reached in the area of internal security.
"However, if the priority in the negotiations becomes avoiding any kind of new cooperation with a country outside the EU, then this political doctrine and ideology will have damaging real world consequences for the security of all our people, in the UK and the EU. As leaders, we cannot let that happen."
The speech is the second of six key addresses by the Prime Minister and senior Cabinet ministers mapping out the Government's plans for Brexit.
"Those who threaten our security would like nothing more than to see us fractured," Mrs May added.
"They would like nothing more than to see us put debates about mechanisms and means ahead of doing what is most practical and effective in keeping our people safe.
"So let our message ring out loud and clear today: we will not let that happen. We will keep our people safe, now and in the years to come."
Speaking to ITV News on Friday, Mr Wainwright said that getting the right security deal post-Brexit was not just important for the UK, but "for the whole of Europe".
Mr Wainwright continued that all major security threats are "international in nature" and "are linked in so many different ways... we've got to stay together".
The 50-year-old continued that technology is enabling new forms of crime and terrorism, and it is this which "worries" him "the most", and "a united European framework" is the way to tackle this.
Asked whether he believed security could be used by the UK as leverage in its negotiations with the EU for a trade deal, Mr Wainwright said he did not believe this would happen since "the grown-ups in the room" know that global security "is really serious business, and I think there's an understanding that reality in the end will drive probably a constructive approach on both sides".
Also in her speech, the Prime Minister said the UK would pull out of major foreign policy arrangements as soon as possible after Brexit.
In a move likely to please Brexiteers, Mrs May said the UK would not wait until the end of any implementation period to take back full control over areas like diplomacy, peacekeeping, defence and aid.
During a question and answer session following her speech, German diplomat Wolfgang Ischinger sparked a round of applause from the audience of diplomats and security experts when he said it would be easier if Britain remained in the EU.
Mrs May then faced a second questioner who suggested Brexit should be ditched.
However, the Prime Minister insisted that Britain is leaving the EU and there will be "no second referendum".
On Friday, Mrs May again insisted Britain's commitment to maintaining European security is "unconditional" when she visited Berlin for talks with German Chancellor Angela Merkel.
But as well as facing tricky negotiations in Brussels to secure a strong agreement, the Prime Minister is also under pressure from Brexiteers in her Party who are fundamentally opposed to the European Court of Justice having any oversight role in a settlement, such as in relation to the European arrest warrant.