NICOLA Sturgeon has sought to dampen speculation about the SNP reinstating a 50p top rate of income tax, as the issue continues to dominate the Holyrood election campaign.

On Wednesday, the First Minister said it would be “daft” and “reckless” to use new powers coming to Holyrood in 2017 to raise the rate from 45p to 50p for those earning over £150,000.

Rather than generate extra funds, such a raise actually could cost money, she warned, as it could prompt many rich individuals to leave Scotland. Sturgeon was praised by the Tories, but attacked as timid by the LibDems and Labour.

On Thursday’s first TV debate, Sturgeon then appeared to change tack and open the door to rises by saying: “I think there should be a 50p top rate of tax.”

But writing in the Sunday Herald today, the First Minister conspicuously tones down her enthusiasm, saying she is “in principle not opposed” to a 50p rate, while warning there is “quite literally no point in introducing one if it could actually end up costing the public purse”.

Ruling out a 50p rate in 2017/18, she says “the issue will be kept under review”.

Labour, which backs a 50p rate, said Sturgeon was in “complete disarray” on the issue and said many of her own supporters would be “bewildered” by the to-ings and fro-ings.

Around 17,000 people in Scotland pay the additional rate, and if all continued to do so, a 50p levy should raise an extra £110 million a year. However, if just 1,300, or 7 per cent, left Scotland in protest, it would cancel out all the potential gains and sink the budget £30m into the red, according to Scottish Government analysis.

Campaigning in Glasgow Pollok with candidate Humza Yousaf yesterday, Sturgeon said the SNP would protect key social benefits in the next five years: tuition fees, free childcare, free school meals, free bus travel, free prescriptions and free personal and nursing care.

“Over the past nine years the SNP government has protected and extended a number of key social benefits – using tax revenue responsibly to pay for policies that protect people’s incomes and mitigate the impact of Tory austerity.

"If re-elected we will double free early years and childcare provision; and extend free meals to children in our nurseries. Support for universal benefits from other parties has been inconsistent, half-hearted or non-existent.”

In a speech in Edinburgh, Tory leader Ruth Davidson admitted those earning over £150,000 could pay more tax, but said the cumulative effect of higher tax rates in Scotland would deter entrepreneurs and investment and ultimately hurt the economy.

“I’m pretty sure that somebody on £150,000 can pay a bit more. I’ve never earned that kind of money, but it doesn’t strike me that those who do are short of cash,” she said. “But that’s not the issue here. The issue is: what’s best for Scotland? What’s in our national interest? What’s going to help jobs? The point is this: tax policy sends messages.”

She said that if the SNP and Labour came first and second in May, Scotland would be trapped on a “a high tax escalator” as the two parties debated “who can tax more”.

She said: "That won't grow jobs – it will cut jobs. That won't boost the economy – it will damage the economy. That won't support our public services – it will pile more cuts on them. It is only us, the Scottish Conservatives, who can stop that escalator in its tracks.”

The Scottish Greens are expected to advocate at least one new band of income tax as well as tax cuts when they unveil their plan, Fair Funding for Public Services, on Tuesday.

A source said: “We will propose that the parliament uses its new powers over rates and bands creatively to reduce inequality. We believe it's possible to use the powers to cut income tax for lower earners so they keep more of what they earn, but increase it for higher earners and overall bring additional revenue to help reverse cuts. Greens as tax-cutters might surprise some, but we see the opportunity to use the new powers creatively while others are reluctant to.”

The package will also propose replacing council tax with a new levy based on updated property values, with the party’s totemic land value tax now a “long-term goal”.

Scottish LibDem leader Willie Rennie called on the SNP to abandon its plan for a 50 per cent, £150m, cut to Air Passenger Duty if it wins the election.

He said: “The so-called progressives in the SNP are arguing for a tax cut that even George Osborne would never consider. It would encourage more environmentally damaging flights just at a time we should be stepping up our efforts to meet our climate change targets."