The euro currency does not work for Greece or Portugal and they will eventually leave the euro zone, an economist told CNBC.

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"They will leave the euro but stay within the European Union because it is very difficult to leave the EU in terms of security policy and foreign policy. You want to be part of it but only linked to it and that is increasingly what a number of countries want to do," Steen Jakobsen, Chief Economist at Saxo Bank said.