The Scottish government has published the details of its proposed referendum on independence.
Under the draft bill, voters would have the option of voting for either new powers for the Scottish Parliament or full independence from the UK.
First Minister Alex Salmond described the Referendum Bill as an opportunity for Scots to have a say on their nation's future.
Opposition parties have said they will vote down the proposals.
The draft bill unveiled by Mr Salmond will now go out to consultation.
The people want our parliament to be able to do more, so the debate is now about how much more
Alex Salmond First Minister
It proposes asking two questions on two separate ballot papers.
Firstly, voters would be asked to vote 'yes' or 'no' on whether they support the Scottish Parliament being given new devolved powers.
The consultation paper offers two alternatives for this question, one based on the so-called "devolution max" option of giving Holyrood control of everything except defence, foreign affairs and financial regulation, and another based on the more limited powers put forward by the Calman Commission.
They will then be asked whether: "The parliament's powers should also be extended to enable independence to be achieved."
Speaking at the launch of the bill at a press conference in Edinburgh, Mr Salmond said he would be campaigning for people to vote 'yes' to both questions.
Will Scottish independence really happen?
He added: "The Scottish government believes in the sovereignty of the people. And as set out in the manifesto on which we were elected, we are committed to giving people the opportunity to express their views in a referendum.
"More than 10 years on from the establishment of the Scottish Parliament, the debate in Scotland is no longer about whether or not the parliament should take on new responsibilities - it is about the form of change, and that issue underpins the consultation.
"The people want our parliament to be able to do more, so the debate is now about how much more. And it is time the people had their say."
Mr Salmond said the case for an independent Scotland is "stronger and more urgent" following the economic crisis.
"It is exactly the powers and flexibility offered by independence that Scotland needs in order to support recovery now, and deal effectively with the challenges and opportunities of the future," he said.
"But I recognise that there are also those who argue that the responsibilities of the Scottish Parliament should be extended in more limited ways."
As always the SNP puts the politics of narrow nationalism ahead of the interests of Scotland
Tavish Scott Scottish Lib Dem leader
Iain Gray, the Scottish Labour leader, dismissed the draft bill as being "nothing more than Alex Salmond's doomed vanity project."
He added: "At a time when Scotland needs action on jobs and economic recovery this is merely another consultation exercise.
"If Alex Salmond believed in his bill he would bring it to the parliament but he knows it would be defeated. He is stalling for time as he doesn't know what to do."
Scottish Liberal Democrat leader Tavish Scott accused Mr Salmond of getting his priorities wrong.
He said: "As always the SNP puts the politics of narrow nationalism ahead of the interests of Scotland.
"There is no majority for a referendum in parliament. There is no support in the country for independence. Independence isn't going to happen."
Scottish Tory leader Annabel Goldie said Mr Salmond should "ditch this bill, stop wasting taxpayers' time and money and get on with what he was elected to do - namely helping the country deal with the legacy of Labour's debt crisis."
The minority SNP government published a white paper on Scotland's constitutional future on St Andrew's Day last year which set out a range of options, including significant new powers for Holyrood as well as its favoured choice of full independence from the UK.
Mr Salmond announced earlier this month that the bill would be published in draft form first, which would prevent opposition parties killing it off before the forthcoming election.
The first minister said at the time he believed opposition parties wanted to "grab control of the Referendum Bill and dispose of it as quickly as they possibly could".
Labour this week accused the Nationalists of trying to "rig" a referendum vote after it emerged ministers want to set up a special body to regulate it.
The creation of a Scottish Referendum Commission to oversee a future poll has been discussed at a meeting of government officials and members of elections watchdog the Electoral Commission.
But Education Secretary Mike Russell insisted setting up a new body to oversee such a poll was the "normal thing to do".
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