Brexit will not affect the UK's security cooperation with NATO allies in France and Germany, intelligence chiefs from all three countries have confirmed.

The three cited growing external threats to the continent's stability in a rare joint statement on Friday from the heads of Germany's BND, France's DGSE, as well as MI6.

“The chiefs … said that all three services would continue to be close allies in jointly protecting Europe from threats such as Islamism, terrorism, organised crime or cyber-attacks,” they said.

“This would also hold true… in view of Brexit,” they added after meeting at the Munich Security Conference.

Britain and the European Union have pledged to continue their cooperation on security issues through institutions like Europol and Eurojust, even after the UK leaves EU on March 29, with or without a deal.

The UK government last month rejected the proposed withdrawal agreement and are no closer to finalising an alternative deal to leave EU, raising the possibility of a disruptive no deal Brexit that could harm relations.

While the trio have denied any outcome will affect their relationship, a proposed “operational cooperation” between police and justice systems remains vague.

British officials did warn that a no deal Brexit could be a backward step in terms of security cooperation.

“Our security relationships are unconditional with our European colleagues… We need each other. This is a two-way street and that isn’t going to change,” Alex Younger, the head of the MI6 foreign intelligence service, said.

The relationship that exists between us and our European partners is closer than I have ever known it in my 30 years as an intelligence officer. Brexit doesn’t fundamentally alter those relationships,” he said.

Director general of France’s Direction Generale de la Securite Exterieure (DGSE), Bernard Emie, said the three countries had to reinforce their cooperation despite the political environment amid the unprecedented threats against Europe.

“The European continent is under growing threat of interference and external aggression,” Emie said. “These challenges cannot be dealt with solely at a national level. They need a strong and coordinated response … especially from our three services.”