Mr Cameron has said in the past that leaving the EU could play into the hands of Britain’s enemies, but this is thought to be the first time he has suggested Isis would actively want to see the UK leave the EU.
The Prime Minister was responding to criticisms of a speech he gave last week, in which he said a new conflict in Europe could not be ruled out. He urged voters not to take a risk on Brexit, saying: “I never said if we leave on Thursday, World War Three breaks out on Friday”.
However, he added that Russian President Vladimir Putin would welcome Brexit, adding “I suspect al-Baghdadi” would, too.
The claim will inevitably lead to further allegations of scaremongering by the Government. However, both campaigns have highlighted the ramifications of leaving or remaining in the EU for Britain’s security against terror threats.
The Leave camp says that Brexit would give the UK greater control over its borders.
The Remain campaign contests this, saying we already have the power to check all passports, and argue that pan-European security networks including Europol and the European Arrest Warrant help keep us safe, and would be put at risk by Brexit.
Donald Tusk, the former Polish Prime Minister, attacked the former London mayor for "political amnesia" over his controversial suggestion likening the EU to the Nazi dictator's plans for domination of the continent.
It comes after the Chancellor George Osborne endorsed the view of the former military chief Field Marshal Lord Bramall, who described Mr Johnson’s remarks as "simply laughable" and "absurd".
The former Mayor had told the Sunday Telegraph that the EU was an attempt to recreate the Roman Empire’s united Europe. “Napoleon, Hitler, various people tried this out, and it ends tragically,” he said.
In the extraordinary intervention, Mr Tusk said he could not "remain silent" in the face of comments by such an "influential" politician.
Mr Tusk added: "When I hear the EU being compared to the plans and projects of Adolf Hitler I cannot remain silent. Such absurd arguments should be completely ignored if they hadn't been formulated by one of the most influential politicians in the ruling party.
"Boris Johnson crossed the boundaries of a rational discourse, demonstrating political amnesia. In some sense, he illustrated a state of mind and emotions of many Europeans, not only from the UK."
But Mr Johnson defended his comments, saying: “Over the last few thousand years there have been all sorts of attempts in Europe to recreate the dream of the Roman Empire and very often that’s been done by force. The EU is different – it’s tried to do it in a more bureaucratic way.
“The problem is there isn’t a single charismatic authority that anyone feels any loyalty to and it’s completely antidemocratic, that’s the problem.
“This discussion is bedevilled by all sorts of artificial media twit-storms or hysteria of one kind or another. There’s a very good argument against the lack of democracy in the EU.
“Over the last 2000 years people have made repeated attempts to unify Europe by force. The EU is a very different project but it is profoundly antidemocratic.”
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