'David Cameron was branded an EU ‘enthusiast’ by Tory Eurosceptics last night as he said Britain must let eurozone countries move towards a United States of Europe with a common economic policy.

The Prime Minister admitted he was not sure whether Germany and other countries had the political will to prevent a break-up of the single currency, but insisted they must be allowed to try – even if that meant closer integration.

The tumult on global financial markets intensified yesterday ahead of a crunch ruling by the German constitutional court on the legality of bailouts for debt-crippled nations.'

Read more: Why Eurozone Should Become United States of Europe, by David Cameron