MINISTERS yesterday published the question proposed for a referendum on the single European currency: “Should the United Kingdom adopt the euro as its currency?” But the wording faced an immediate challenge from the Conservatives and the No Campaign, who branded it biased and unfair. Gordon Brown announced the draft euro Bill as part of his pre-Budget Report in the Commons, fulfilling a pledge in this year’s Budget to set out the terms on which a referendum would be conducted if the Treasury agreed that the conditions were right and Parliament approved the ballot.

The question, contained in the draft Single European Currency (Referendum) Bill, will be assessed by the independent Electoral Commission once the Bill is introduced in Parliament.

In a move that will come as a relief to the No Campaign, the Bill bans voters from European Union countries except Irish citizens, who are eligible to vote in parliamentary elections. The Bill also sets out a ten-week timescale for the referendum.

Ministers insist that they followed the Commission’s guidelines in drawing up the question, which states that “words and phrases used in the question should not have positive or negative connotations”.

But Alan Duncan, Tory Constitutional Affairs spokesman, said: “The proposed referendum question breaches Electoral Commission guidelines on fair wording. It makes no mention that the pound would be replaced if people vote “yes”. A fair question would make clear the implications for our existing national currency.

“The Government is using sleight of hand to hide a euro referendum fix.”

Matthew McGregor, a No Campaign spokesman, said: “Sometimes people think you can have the euro and the pound but they are not making it clear that to have the euro you must scrap the pound. We also think they may have breached the Electoral Commission guidelines on language. The word ‘adopts’ is quite a beneficial, nice thing which sounds like a loaded word to us.”

Britain in Europe welcomed the draft Bill. Danny Alexander, a spokesman, said: “The question seems perfectly straightforward and unexceptional. The debate during a referendum campaign would make perfectly clear what is at stake and I think concerns about the question are just silly.” He added: “These are welcome steps along the road to the euro but until a decision is taken, Britain will continue to pay an economic price for being outside the euro.”

Ministers emphasised yesterday that publication of the draft Bill was not a comment on the timing of a referendum, which remains dependent on the Chancellor’s verdict on the five economic tests. Gordon Brown will spell out progress towards the tests in his next Budget in the spring, and a referendum still seems unlikely before the next general election. The first scrutiny of the Bill may be in the new year by MPs on the Constitutional Affairs Select Committee.

The Bill makes allowance for a euro referendum to be held alongside another election but does not pass judgment on whether it should be by postal or conventional ballot. It sets out powers for the Electoral Commission to select one group to receive state funding to put the case for, and one to put the case against.

A spokesman for the Department for Constitutional Affairs said: “The draft referendum question has been drafted using guidelines produced by the Electoral Commission and covering the intelligibility of referenda questions. The commission has a statutory obligation to assess the question, and will formally review it at the time a Bill is introduced in Parliament.”

He added: “The electorate for the referendum would mirror that for the 1975 referendum on EEC membership. The Government will report on progress of its reform agenda in the Budget. The Government can then consider the extent of progress and determine whether on the basis of it the Government makes a further Treasury assessment of the five tests, which — if positive — would allow it to put the issue before the electorate in a referendum.”

Menzies Campbell, the Liberal Democrat foreign affairs spokesman, said: “In the event that a referendum took place there would be no one in the country that did not realise that by joining the euro we were in effect giving up the pound . . . It would be perfectly obvious what the alternatives were.”