Scotland's governing party set out its plans today for a referendum on independence.
The Scottish National Party's (SNP) campaign could lead to an increase in the Scottish parliament's limited powers in a challenge to the authority of Britain's prime minister, Gordon Brown, himself a Scot.
But the main opposition parties have vowed to block any move to end the 300-year-old union with England.
"Today is . . . the start of the next and, I hope, the most dynamic phase of Scotland's programme of constitutional reform," SNP leader Alex Salmond told a news conference.
He published draft legislation that, if passed, would lead to a vote on a "full independent state" and that also called for a national debate on other options for change, including more powers for the Edinburgh-based parliament.
The pro-independence SNP became the largest parliamentary force in May elections, ending 50 years of political dominance in Scotland by the Labour Party.
The three other main parties - Labour, the Conservatives and the Liberal Democrats - oppose a referendum on independence ,and opinion polls show average support for ending the union at about 30 per cent.
The parties, in an joint statement ahead of Mr Salmond's announcement, said an independence vote would damage Scotland, although they agreed there was a case for reviewing the limited powers exercised by the Scottish parliament and executive set up in 1999.
"We are willing to enter into debate jointly about the way in which devolution within the UK can best develop in the years to come," said the statement. Mr Salmond said the statement was a sign the argument on more powers for Scotland was shifting his way.