The European Union is pursuing a similar goal to Hitler in trying to create a powerful superstate, Boris Johnson says.

In a dramatic interview with the Telegraph, he warns that while bureaucrats in Brussels are using “different methods” from the Nazi dictator, they share the aim of unifying Europe under one “authority”.

But the EU’s “disastrous” failures have fuelled tensions between member states and allowed Germany to grow in power, “take over” the Italian economy and “destroy” Greece, he warns.

Mr Johnson invokes Winston Churchill’s war-time defiance, urging the British people to be “the heroes of Europe” again, set the country free and save the EU from itself by voting to leave in the referendum next month.

The former mayor of London, who is a keen classical scholar, argues that the past 2,000 years of European history have been characterised by repeated attempts to unify Europe under a single government in order to recover the continent’s lost “golden age” under the Romans.

“Napoleon, Hitler, various people tried this out, and it ends tragically,” he says.

“The EU is an attempt to do this by different methods.

“But fundamentally what is lacking is the eternal problem, which is that there is no underlying loyalty to the idea of Europe. There is no single authority that anybody respects or understands. That is causing this massive democratic void.”

Mr Johnson’s potentially inflammatory comparison to Hitler comes at a critical time in the referendum campaign, with senior Tories on either side publicly attacking each other in blunt terms.