The 10 new members of the European Union could damage the single currency and themselves if they rush to join the euro, a senior European Union economic official warned yesterday.

Mr Caio Koch-Weser said he was concerned that some countries had set themselves an "over-optimistic" timetable for trying to join the euro.

Mr Koch-Weser, Germany's top finance ministry official, is the new chairman of the EU's traditionally secretive economic and financial committee, which vets bids to join the euro-zone currency.

He thinks the new EU members, most of which are former communist states, need to ensure their economies are straight before joining the single currency.

Rushing to join the bloc, with its single monetary policy, could be harmful to the economies of the candidate countries and to the credibility of the euro.

In a rare briefing to journalists, Mr Koch-Weser said he was concerned about the "over-optimistic dates" being set by some countries to join the exchange rate mechanism - the precursor to full euro membership.

Countries such as Poland, Hungary and Slovakia, which join the European Union in May 2004, have indicated that they would like to join the single currency by 2008.

But Mr Koch-Weser said some countries still had high deficits, high unemployment and that proceeds from earlier privatisations - used to consolidate public finances - were now harder to find.

"Convergence is more difficult for some in this phase than it was in the first phase," he said.

He repeated the view that new member-states would have to prove they could maintain close exchange rate stability with the euro before they joined.

Decisions to admit the countries to the euro zone, already beset by high deficits and internal divisions, would be based on tough economic criteria, he said.

Mr Koch-Weser's committee, which does much of the detailed work ahead of monthly meetings of EU finance ministers, is facing an intensely difficult period in the months ahead.

He admitted that the open divisions between euro members over the rise in national deficits - and the crumbling of the EU's budget rules - were a cause for concern.

"It makes our work very hard and very challenging," Mr Kock-Wessler said.  - (Financial Times Service)