A Government adviser is facing calls to quit after he compared Brexit to the appeasement of the Nazis in the 1930s.

Lord Adonis also compared the decision to leave the EU to the fall of the British Empire and said it will lead to a period of 'serious relative decline' in living standards compared to Germany and France.

His comments sparked outrage and Conservative MPs called on him to resign from his role advising the government on infrastructure projects.

Lord Adonis, a Labour peer, said: 'My language is usually pretty subdued in politics but anyone with a historical sense – and I'm a historian – recognises that leaving the economic institutions of the European Union, which have guided our destiny as a trading nation for half a century, is a very big step and the importance can't be over-emphasised.

Lord Adonis has sparked fury after he compared the decision to leave the EU with the appeasement of Hitler during the 1930s

'To my mind, it's as big a step that we're taking as a country as decolonisation in the 1950s and 60s and appeasement in the 1930s.

'We got it right on decolonisation, we got it wrong on appeasement and I think we're in serious danger of getting it wrong in the way that we leave the EU.'

In the interview with The House magazine, he said quitting the Brussels club will harm Britain's economy.

He said: 'If we can't have our cake and eat it then we face a serious relative decline in our living standards compared with France and Germany and I don't believe the British people will put up with that.

'So we would, in that event, I believe face a crisis. It may be a crisis played out over quite a number of years – which, after all, is what happened with appeasement – but there will be a crisis.

The Labour peer said quitting the Brussels club will turn out to be as big a mistake as not standing up to the Nazis as hey rose to power in Germany

'It's important for political leaders like me to sound the alarm bell because it's important to understand what might be at stake: in 18 months' time, people may require visas to go to France.

'Can you imagine what the Great British public is going to think?'

But his comments were branded 'appalling and wrong' by a shocked MP who demanded his resignation.

Peter Bone, the Conservative MP for Wellingborough, told the Mail Online: 'Words almost fail me.

'First of all, to suggest that what this government is doing is in any way related to appeasement is outrageous.

'What we are doing is taking power back to this country form a European superstate, not giving power to some a European fascist empire.

'Using this sort of appalling language is wrong, his arguments are wring and his tone is wrong.

'And if he is a government appointed chairman of some quango then he should go - he should either resign tonight and if he doesn't he the should be fired tomorrow.'