The question Scottish people will be asked in a referendum on independence is biased in favour of a 'yes' answer, according to MPs.
The SNP government in Edinburgh, which is in favour of independence, plans to hold a poll on the break up of the United Kingdom before 2015 and has proposed that Scots be asked: "Do you agree that Scotland should be an independent country?"
However in a report published on Tuesday, the House of Commons Scottish Affairs Committee has said that such a question was a "leading question".
"This referendum must be, and be seen to be, fair and acceptable to those on both sides of the argument. It is
essential that the result commands wide acceptance," the MPs say.
The MPs conclude that the Electoral Commission must be tasked with coming up with a question that is "clear and fair" and does not favour one side of the debate.
"No question should be placed before the electorate unless the Electoral Commission is completely satisfied as to the intelligibility and fairness of the wording.
"The Commission should conduct a very thorough programme of testing of a number of different question options before coming to a view on the wording which is clearest and fairest."
Ian Davidson, the Labour chair of the committee, said it was unfair to have a referendum "in which separatists are both player and referee".
"That goes against every notion of fairness and transparency," he said.
"It must be for the Electoral Commission, an experienced and neutral body, to oversee the process and, crucially, to test alternative questions and words to make sure that any referendum question will be clearly understood."
But Scottish Government cabinet secretary for parliamentary business Bruce Crawford said the Westminster report was "devoid of credibility".
"The Scottish Government's proposed referendum question is straightforward and fair," he said.
He added: "The ballot paper will be subject to testing during autumn and winter this year, and we will be delighted to receive advice from the Electoral Commission and other electoral professionals."