Parties must unite to stop Scots independence - Darling
Cameron and Miliband unite to oppose Scots independence
(about 2 hours later)
Former chancellor Alistair Darling has urged Labour, the Conservatives and the Lib Dems to unite to defeat those pushing for Scottish independence.
David Cameron and Ed Miliband have jointly urged Scotland to reject calls for independence if a referendum is held on the subject .
The Labour MP for Edinburgh South West told the BBC it was "terribly important that we fight this thing together".
The prime minister told MPs he believed "passionately" in the Union, while the Labour leader said its break up would be damaging to the UK's economy.
Scotland's First Minister Alex Salmond has said he will hold a referendum on independence in autumn 2014.
Scotland's First Minister Alex Salmond has said he will hold a referendum on independence in autumn 2014.
Ministers in London - who favour an earlier vote - say any referendum would be unlawful without their approval.
But the coalition says any a vote would be unlawful without their approval.
Scottish Secretary Michael Moore told the House of Commons on Tuesday there would be a consultation on how to hold a referendum and he hoped to work with the Scottish National Party (SNP) government to resolve the dispute.
The Conservatives, Liberal Democrats and Labour are opposed to Scottish independence and the leaders of all three parties have promised to fight against the cause championed by Mr Salmond's Scottish National Party (SNP).
David Cameron has said he believes it is "very unfair" on the Scottish people not to have plans for a "legal, fair and decisive" referendum in place - although he has insisted he is not trying to "dictate" to Holyrood.
The Scottish government insists it can go ahead with a referendum without the need for a law to be passed at Westminster - but the coalition disputes this.
'Work together'
At Prime Minister's Questions, Mr Cameron called for cross-border talks with Scottish ministers in an effort to end the constitutional dispute.
The Conservatives, Liberal Democrats and Labour are all opposed to Scottish independence and the leaders of all three parties have promised to fight the SNP's cause.
'Never-endum'
But BBC Scotland's political editor Brian Taylor said there was some disquiet among Lib Dems about Mr Cameron's intervention.
He told MPs: "I passionately believe in the future of our United Kingdom. I passionately believe we are stronger together rather than breaking apart.
He said some believed the prime minister had not adopted a sufficiently conciliatory tone and seemed like he was trying too hard to crush Mr Salmond.
"Frankly I'm sad that we are even having this debate because I support the United Kingdom so strongly.
Speaking to BBC Radio 4's Today programme, Mr Darling said a united front from Westminster was vital.
"But we have to respect the fact that Scotland voted for a separatist party at those Scottish parliamentary elections, so the first thing it is right to do is to make clear the legal position about the referendum."
"The last thing Scotland needs is for this to be posed as somehow an SNP government in Edinburgh up against a Tory government in London.
But he said: "Too many in the SNP are happy to talk about the process; they don't want to talk about the substance.
"That would be very, very bad... That's what Salmond wants it to be, it suits him down to the ground."
"I sometimes feel when I listen to them it's not a referendum they want; it's a never-endum. Let's have the debate and let's keep our country together."
He continued: "I think it's important for people in my party to be prepared to work with Liberals, with Conservatives, people who are in no political party at all.
Mr Miliband agreed, telling the Commons: "We are stronger together and weaker apart."
"We've got our disagreements on other issues and so on, but this campaign is only going to be won if it is fought in Scotland... by people who have got Scotland's best interests at heart."
He called for "immediate cross-party talks" in Scotland about the timing of the vote and the nature of the "single question" which would be asked in a referendum.
Labour leader Ed Miliband has said he will "definitely" get out to campaign against independence.
Meanwhile, Labour's former chancellor Alistair Darling has called for his party, the Conservatives and the Lib Dems to work together to oppose the SNP's plan.
"I think a cross-party campaign will be led by people of grit and steel right across the political spectrum, but there are also people in the Labour Party who will be prominently involved in the campaign, including me," he said.
He told BBC Radio 4's Today programme: "The last thing Scotland needs is for this to be posed as somehow an SNP government in Edinburgh up against a Tory government in London.
Consultation
"That would be very, very bad... That's what Salmond wants it to be. It suits him down to the ground."
In his statement to MPs, Mr Moore said the government's "clear view" was that the power to hold a referendum was "reserved" to Westminster under devolution laws passed in 1998 and that the Scottish government could not authorise a referendum on its own.
The SNP says it is "entirely confident" of its plans to bring in a Referendum Bill setting up a vote for autumn 2014.
But the SNP have said they are "entirely confident" of their plans to bring in a Referendum Bill setting up a vote for autumn 2014.
But the Westminster government argues that any referendum should take place "sooner rather than later".
Mr Darling said that while it was important to clarify the legal position, time should not be wasted discussing "process" when the realities of independence - for example, whether it would mean Scotland joining the euro - were far more important.
In his statement to MPs on Tuesday, Scottish Secretary Michael Moore said the government's "clear view" was that the power to hold a referendum was "reserved" to Westminster under devolution laws passed in 1998 and that the Scottish government could not authorise a referendum on its own.
Mr Salmond said the problems surrounding the referendum flared because Mr Cameron had suddenly decided to "start pulling strings and setting conditions", but said he believed that would only increase support for independence.
If Westminster and Holyrood fail to resolve the legal issue it could end up being ruled over by the Supreme Court.
The first minister has said he will hold a consultation on the precise question to be asked in the referendum.
Westminster favours a straightforward yes or no to independence, but a third option - so called "devolution max" - could also be added.
This would give voters the chance to opt for increased powers for the Scottish Parliament - for example over monetary policy - without gaining full political independence.
The SNP says it prefers a yes/no choice, but it accepts there is "a significant body of opinion" in Scotland which favours the other option.
It is thought that "devo max" would be harder for Westminster to defeat because it would split the unionist vote.
Under the Scottish government's timetable, a referendum bill would be introduced at Holyrood in January 2013, it would be expected to be passed by the autumn and gain Royal Assent later in 2013.
