Families driven from their homes during the Second World War, gay rights and a recalcitrant Czech President emerged as the last hurdles for a treaty to restructure the European Union.

Furious EU leaders are determined to prevent President Klaus from delaying or amending the Lisbon treaty before appending his signature, the last needed to complete the document. Mr Klaus said yesterday that he wanted the same opt-outs as Britain and Poland from the Charter of Fundamental Rights, a key section of the treaty, to stop the European Court of Justice from gaining extra powers over Czech judges.

Mr Klaus said that he feared the treaty would give thousands of German families expelled after the war the right to reclaim property in Sudetenland. EU officials said that he had not raised the issue during talks and that his explanation for refusing to sign was a delaying tactic to cause disruption to an institution that he detests.

The 66-year-old leader’s demands have dampened the delight in EU capitals over Ireland’s “yes” vote for the treaty in its rerun referendum a week ago and over the agreement of President Kaczynski of Poland to ratify the document in Warsaw today. EU leaders are desperate for the treaty to come into force as soon as possible so that they can appoint a president and foreign minister, created by the treaty, as well as the new members of the European Commission, who are due to start on November 1.

Leaders still intend to discuss at a summit on October 29 whom they want as president — Tony Blair is a leading contender — and foreign minister. It is possible that a consensus over the top post will emerge but it will be a provisional choice, a president-elect, pending Czech ratification.

Legal experts from the EU said that, depending on the precise nature of the extra wording demanded by Mr Klaus, the document might have to go back to all 27 capitals for another round of ratifications. New guarantees given to Irish voters were backed by leaders meeting at the European Council and it is possible that a similar arrangement can be made this month over Mr Klaus’s demands. This might enable him to sign the treaty but claim victory at the same time.

In an interview with The Times, Gordon Bajnai, the Hungarian Prime Minister, said that Mr Klaus’s tactics were “completely counterproductive and hindering Europe’s recovery” from the economic crisis. “I am one of those European prime ministers, actually the majority of them, who are quite impatient about getting the Lisbon treaty on track. We are obviously doing everything to pursue it,” he said.

Mr Klaus has showed no sign of a compromise. “As you know, I have always considered this treaty a step in the wrong direction,” he said.

“It will deepen the problems the EU is facing today, it will increase its democratic deficit, worsen the standing of our country and expose it to new risks — among other things also because it endangers the legal status of the citizens and the stability of property rights in our country.”

The row could trigger a political crisis in the Czech Republic. One EU diplomat said: “At no point did the Czech Government ask for this opt-out during treaty negotiations. The ball is now in the court of the Czech Prime Minister, Jan Fischer — he’ll have to decide if he wants to risk reopening the treaty negotiations.”Mr Fischer said that his Government will consider its position on Monday.

How to avoid Czech-mate

Option 1: It is decided at home The Czech Government rejects Klaus’s call for an opt-out. If the President then refuses to sign, could the Government find a way to circumvent him, as when he refused to sign a gay rights law?

Option 2: The fudge The Government backs Klaus’s call for an opt-out that could be agreed readily by European leaders at the next EU summit on October 29. Klaus could sign and the treaty would come into force, probably on December 1

Option 3 Return to go The Czech Government backs Klaus’s call for an opt-out but EU lawyers rule that it must be ratified, again, by all 27 member states. This might delay the treaty long enough for David Cameron to call a referendum on it if he wins the next election

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