Mr Greenspan, chairman of the Federal Reserve from 1987 to 2006, said: "I believe [Greece] will eventually leave. I don't think it helps them or the rest of the eurozone - it is just a matter of time before everyone recognises that parting is the best strategy.

"The problem is that there there is no way that I can conceive of the euro of continuing, unless and until all of the members of eurozone become politically integrated - actually even just fiscally integrated won't do it."