ALMOST 30% of SNP backers do not want independence and would prefer to see extra powers for Holyrood instead, according to a poll published today.

The telephone snapshot puts the number of Nationalist supporters backing independence at 63%, while 28% prefer a devo-plus option of giving Holyrood more control over tax and borrowing powers to meet its spending pledges.

The policy would leave Westminster responsible primarily for VAT and National Insurance with most other taxes devolved to Holyrood. Devo-plus differs from devo-max, which envisages handing over all tax powers to the Scottish Parliament.

The figures emerged in a breakdown of the Ipsos Mori survey of 1000 people for the independent think-tank Reform Scotland.

The poll's headline numbers had been published earlier and showed 29% of people favoured the status quo, 27% independence and 41% devo-plus.

Asked if Scotland should remain part of the UK with unchanged devolved powers, 66% of Conservative supporters agreed as did 37% of Labour, 40% of Liberal Democrat and 6% of SNP supporters, plus 31% of non-aligned voters.

Asked if Scotland should remain part of the UK but with devo-plus powers, 30% of Tory supporters agreed as did 52% of Labour, 53% of LibDems and 28% of SNP supporters, as well as 50% of non-aligned voters.

Asked if Scotland should become fully independent and "separate from the rest of the UK", 1% of Tories agreed as did 7% of Labour, 3% of LibDems, 63% of SNP supporters and 17% of non-aligned voters.

The poll also showed that, when asked if the anti-independence parties should campaign for more powers for Holyrood, 58% of Tory supporters agreed as did 73% of Labour, 74% of LibDems, 64% of SNP and 67% of non-aligned voters.

A Reform Scotland spokesman said before people were asked a number of questions, devo-plus was explained to them.

Ruth Davidson, the Scottish Conservative leader, described the poll as a "damning verdict" on Alex Salmond's failure to provide hard facts about what independence would mean for Scots. She argued it was no wonder the First Minister was "desperate to get a second question on the referendum ballot paper when his own supporters are now getting cold feet about separation".

She added: "Let there be no doubt, this is a vote between separation and devolution and the people of Scotland should be offered a single question that is fair, legal and decisive."

Patricia Ferguson, Scottish Labour's Constitution spokeswoman, said: "This is yet further proof that not only is independence unpopular with the Scottish people, it's also not something that huge numbers of SNP voters really want."

She insisted the Nationalists had a mandate to hold a referendum on independence "and that issue alone, not anything that the SNP and Alex Salmond think they can use to get themselves off the hook".

In contrast, the SNP said the snapshot was bad news for the Better Together campaign as it showed almost three-quarters of Labour voters wanted their party to campaign for more powers for Holyrood.

Angus Robertson, the SNP campaign director, said: "This poll is disastrous for the anti-independence parties, who stubbornly refuse to listen not only to their own supporters but also to the substantial body of opinion across Scotland calling for a more powers option."

He said that while the SNP would campaign for independence in the referendum it also recognised there was a "real debate to be had about bringing proper job-creating powers to the Scottish Parliament".

Mr Robertson added: "The question Johann Lamont and Margaret Curran have to answer is why they want decisions for Scotland to continue to be made by a Tory government Scotland rejected, instead of a Scottish Parliament 100% elected directly elected by people in Scotland?"