Deficits remain obstacle for new EU members

"Most of the accession countries have made big progress in bringing down inflation and reducing their budget deficits," Padoa-Schioppa told the business daily Handelsblatt.

"Some of them have good chances of meeting the convergence criteria in time to adopt the euro at an early stage. But other countries need more time. Generally speaking, attaining sustainably healthy public finances is frequently the last remaining hurdle," the ECB official said.

Even though some of existing eurozone countries are currently in breach of the European Stability and Growth Pact, a tight corset of budget rules governing eurozone membership, Padoa-Schioppa said the incoming EU members could not be let off the hook.

"It's not just the ECB, all European institutions recommend that the Maastrict criteria be applied strictly," Padoa-Schioppa said. "They were valid for the 'old' eurozone members and there is no reason to turn away from them."