Jim O'Neill, chairman of Goldman Sachs Asset Management, has warned the need for German-led fiscal integration in the eurozone would make it increasingly difficult for all countries to stay in the single currency.
O'Neill, whose division manages more than $800bn (£500bn) of assets, said countries as diverse as Portugal, Ireland, Finland and Greece could pull out of the single currency rather than have to operate under a single eurozone treasury.
"The Germans want more fiscal unity and much tougher central observation - with the idea of a finance ministry," O'Neill said in an interview with The Sunday Telegraph.
"That will emerge for those that want to stay in this damn thing, or can stay in.
"With that caveat, it is tough to see all countries that joined wanting to live with that-including the one that is so troubled here [Greece].
"If you wind the clock back, it was pretty obvious that economically probably only Germany, France and Benelux of the original joiners were the ones that were ideal for a monetary union.
"For [them] it is not a bad idea - these countries have always had some kind of tight fixing of exchange rates and are very intertwined. For all the rest that originally joined - Spain, Italy, Portugal, Ireland, Finland - it is actually questionable."
O'Neill said because Finland and Ireland were adjacent to non-eurozone countries they might prefer to quit the euro but the single currency might be stronger as a result.