Romania waves the white flag in Schengen battle

For his part, foreign minister Teodor Baconschi, who first made the Croatia attack, apologised in an interview with the NewsIn news agency. "It was a mistake, from a psychological point of view, that the Schengen entry became such a big stake," he said.

The whole affair comes after France and Germany in December said Romania should not be allowed to get into the passport-free Schengen zone unless it first makes progress in the Co-operation and Verification Mechanism (CVM), an anti-corruption monitoring procedure imposed by the EU in 2007.

Mr Baconschi later suggested Romania could put hurdles on Croatia's EU accession road, while Romanian MPs said they would delay ratification of a Lisbon Treaty protocol on letting 18 new MEPs join the EU parliament.

The Romanian president on TV on Thursday noted that Bucharest would have been "technically" ready to go into Schengen in spring 2011 as planned.

He also voiced anger at French and German leaders for keeping him in the dark at the EU summit in December about their plans to block the Schengen move just one week later.

"The problem is not so much that our Schengen entry will be delayed by a few months ... but the abuse. Either we are equal partners or not," he said.

"It was overnight and without a warning. I would have expected that one of my colleagues in the Council - either Mr Sarkozy or Ms Merkel - to say 'look, Mr President, we will be against it.' But they didn't and you know that normally in the Council there is talk about solidarity."

Speaking to EUobserver on an anonymous basis, an EU official admitted that the Schengen blockade is "unfair" in technical terms because there is no official link between the CVM and the Schengen process. But the contact added that it is "logical" that a country riddled with problems on corruption and organised crime is a threat to Schengen security.

An EU diplomat said: "It's not only about having the equipment and meeting all technical standards, it's also about the quality of the system and making sure that the people within respect all the protocols."

Meanwhile, Sandor Pinter, the interior minister of Hungary, which took over the EU presidency last week, in Budapest on Thursday said his country will try to broker an EU political agreement on Schengen enlargement by the end of June.

"I am an optimist - I never regard anything as a lost case ... We are aware of the German and French positions, but there is a defined course of legal steps of action that has to be followed," he said.

"By June the latest, we will have to achieve a political decision which sets out what tasks need to be carried out and with what deadlines, so that they are able to change the point of view taken by France and Germany."