...member Klaus Liebscher said on Sunday.
Liebscher said in a speech prepared for delivery to an Austrian National Bank conference that countries must meet the economic benchmarks for adopting the euro and show they can continue to meet them.
"In the interests of the members of the euro zone as well as those of the accession country, quality must come before speed," he said.
Slovenia is so far the only one of the new EU member states to have joined the euro zone, but Malta and Cyprus adopt the common currency in January and others are waiting in the wings.
Economic and Monetary Affairs Commissioner Joaquin Almunia said on Friday that rising inflation in Slovenia set a bad example for other countries hoping to join.
He also said that when assessing in May Slovakia's readiness to join the euro zone in 2009, the Commission would need to look carefully at how sustainable its low inflation path was.
Liebscher did not comment on euro zone interest rates or current economic conditions in his speech, after the ECB left rates on hold at 4 percent on Thursday.
He said the euro had won recognition as an international currency second only to the U.S. dollar and monetary policy had succeeded in maintaining price stability, which was a necessary condition for sustainable growth and employment. (Reporting by Krista Hughes; Editing by Gerrard Raven)
Keywords: ECB/LIEBSCHER
[FRANKFURT/Reuters/Finance.cz]