Enlargement Commissioner Olli Rehn said the pace of expansion will slow down after Romania and Bulgaria join the bloc, the next wave expected no earlier than 2009.
"As we have still many years before the next accession, we should indeed focus on improving the immediate functioning capacity of the current EU now, not only the more abstract absorption capacity in the distant future," Rehn said in a speech to the European Policy Centre think-tank.
"The current enlargement countries are chugging along the track to the EU, not rushing towards accession like the Eurostar or a high-speed train," Rehn said. "But it would only undermine our own conditionality and our own strategic interest if we gave them the impression that they are on the road to nowhere," he added.