Senior Tories who are backing a 'Brexit' have rallied to support Boris Johnson after the former London Mayor compared the European Union to Hitler’s Nazi Germany.

Chris Grayling, the Leader of the House of Commons, former Cabinet ministers Iain Duncan Smith and Lord Lamont, as well as Tory MP Jacob Rees-Mogg, defended Mr Johnson’s remarks.

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

In an interview with The Sunday Telegraph, Mr Johnson warned that while bureaucrats in Brussels are using “different methods” from the Nazi dictator, they share the aim of unifying Europe under one “authority”.