One of the founding fathers of the single currency and a former chief economist at the European Central Bank has warned that some nations may not be able to remain inside the euro.
Otmar Issing, in a book published this week, said: "Everything speaks in favour of saving the euro area. How many countries will be part of it remains to be seen."
Issing added that funds could not be channelled indefinitely to nations that did not reform their economies. "One has to consider whether one can keep giving money to a country that has not yet fulfilled an obligation, which is still non-transparent, more or less fudges things," he wrote.
Issing said he understood why some of his fellow Germans are nostalgic for the days of the Detuschemark, but he warned against pushing for the end of the euro and a return to national currencies. "Even in its short existence, the euro has been more stable than the mark" he wrote. "One should focus on bringing the euro back to what it was meant to be, a stable currency, stabilised by an independent central bank, which follows a clear mandate".
Before joining the European Central Bank, Issing was on the board of Germany's respected Bundesbank.