Scottish ministers do not have the power to hold a a legal referendum on independence, MPs have heard.
Ministers believe that if the SNP-led Scottish government tried to go ahead with a poll it would be challenged in court and would lose, Scottish Secretary Michael Moore said.
Mr Moore made the comments in a statement to the Commons on 10 January 2012, as he launched a public consultation on staging a referendum on whether Scotland should leave the union.
The Scottish secretary said that the rules in any vote must be "demonstrably above board", and that the referendum should be "legal, fair and decisive".
The Electoral Commission, or an independent body like it, should be involved in staging the vote, Mr Moore said, adding that Scotland's future should not be decided "in secret, behind closed doors nor by wrangling in the courts".
He told MPs: "This is not about the mandates of Scotland's two governments or who calls the shots.
"It is about empowering the people of Scotland to participate in a legal referendum. That means that the UK government is willing to give the Scottish parliament the powers to hold a referendum which they otherwise cannot do legally."
Shadow Scotland secretary Margaret Curran called on Mr Moore to provide assurances that the legal advice he had received was based on "a sound foundation".
Ms Curran called for any legal advice to be made public - a sentiment backed by former Liberal Democrat leader Sir Menzies Campell.
"I'm well aware of the convention that governments do not publish legal advice. But this is a decision that can almost be described as unique because it would bring to an end hundreds of years of history," Sir Menzies said.
"In those circumstances can I urge you to consider again whether the advice received by the government should not be published so as to achieve a degree of clarity?"
Sir Menzies said he welcomed Mr Moore's announcement because "political, economic and social uncertainty for the next two years would be deeply, deeply damaging for the people of Scotland".
But the SNP's leader in Westminster Angus Robertson accused the coalition of trying to "dictate" the terms of the referendum.
"The Conservative Party, the Liberal Democrats and the Labour Party opposed an independence referendum and each one of these parties lost heavily in the election.
"So, why is it that this Westminster government is trying to dictate terms about the referendum to the democratically elected Scottish government, which has a mandate on this issue?" Mr Robertson asked.