A High Court judge called on the government on Friday to delay formal ratification of the European Union's Lisbon treaty until he has ruled on a legal bid to force a referendum.
Parliament approved the treaty last week and it was written into law, but the process is not formalised until a series of documents are signed and what is known as an instrument of ratification is deposited in Rome.
The High Court is reviewing whether it is legal to ratify the treaty without a referendum in a case brought by eurosceptic millionaire and opposition Conservative Party donor Stuart Wheeler.
Lord Justice Richards, who is hearing the case, urged the government to hold off completing ratification until his ruling.
"The court is very surprised that the government apparently proposes to ratify while the claimant's challenge to the decision not to hold a referendum on ratification is before the court," Richards wrote in a letter sent to Prime Minister Gordon Brown and the Foreign Office.
"The defendants are invited to stay their hand voluntarily until judgement," he wrote, adding the court expected to rule on the case next week.
Brown, speaking at an EU summit in Brussels, said the government would not complete ratification until it had heard the court's ruling, although he did not suggest the government was delaying the process in any way.
"The judge has now replied that he intends to give his judgement next week and of course that fits in with our timetable, where having had the Royal Assent, we have to go through all the different procedures before ratification," he said.
"So ratification will not take place of course until we've had the judgement," he added.
Wheeler welcomed the judge's ruling, saying pressing ahead with ratification before the ruling would be "an insult to the court and to the people of Britain".
Wheeler says he is bringing the action on behalf of all Britons who want a say on the treaty in a referendum.
He argues, like the Conservatives, that Labour promised a referendum in its election manifesto and that the treaty is of immense importance and so requires one.
