Bulgaria, the Czech Republic, Hungary, Latvia, Lithuania, Poland and Romania said the euro zone they thought they were going to join, a monetary union, may very well end up being a very different union entailing much closer fiscal, economic and political convergence.
The new EU members which joined bloc during the fifth enlargement wave (2004-2007) are all obliged to adopt the euro under the terms of their accession treaties. Of these, Slovenia, Malta, Cyprus, Slovakia and Estonia have already joined the euro zone. Countries from previous enlargement waves are not obliged to adopt the single currency.
"All seven countries agree to state that a change in the euro zone's legal status could change the conditions of their adhesion treaties," which "could force them to stage new referenda" on euro take-up, said a diplomatic source close to the talks.
The seven capitals are also demanding that non-euro countries that want to engage in eurozone talks "on the possible reforms" should be entitled to do so. Discussions between eurozone countries are normally closed to outsiders.
"It is logical that countries who have a destiny to join the euro meet," said Polish European Affairs Minister Mikolaj Dowgielewicz.
Before the eurozone crisis, several new members that have been close to fulfilling the Maastricht criteria to join the euro zone, including Poland and Bulgaria, had set themselves ambitious plans to speedily join the common EU currency.
More recently, several Polish officials have stated that the country has shelved its plans for early eurozone accession, until it becomes clear what future should be expected for the common EU currency.
Last April, Hungary indicated that it would seek an opt-out from the euro zone. More recently, Czech Eurosceptic President Václav Klaus said that the EU currency club was a "failure" and that his country should get a permanent opt-out from its obligation to adopt the euro.