NICOLA Sturgeon has signalled she is willing to ditch the SNP’s manifesto promise to freeze the basic rate of income tax paid by 2.2million hard-working Scots.

The First Minister refused to rule out hiking the 20p rate for the rest of the parliament, despite her election pledge, saying instead she had an “open mind” about tax choices.

Scottish Tory leader Ruth Davidson said Ms Sturgeon was coming for people’s paychecks.

Ms Sturgeon announced on Tuesday that she wanted a cross-party debate on the “progressive use” of Holyrood’s tax raising powers to fund public services.

This was seen as a reference to tax rises for the 360,000 Scots paying the 40p higher rate that starts at £43,000, and the 17,000 paying the 45p additional rate that starts at £150,000.

However Ms Sturgeon’s comments suggest most Scottish adults, the 2.2m people who pay only the 20p rate of income tax, could be affected be a change to the system next year.

Ministers have promised a paper in the autumn setting out a range of income tax options, including increases and changes to thresholds and the number of tax bands.

Drawing on the policies of all the Holyrood parties, the paper is intended to find common ground on tax so the minority SNP administration can pass its 2018/19 budget.

The SNP manifesto at the 2016 Holyrood election stated the party would “freeze the basic rate of income tax throughout the next Parliament to protect those on low and middle incomes”, raise the tax-free allowance to £12,750 by 2021/22, raise the higher rate threshold by no more than inflation, and possibly raise the 45p rate from 2018/19.

At First Minister’s questions, Ms Davidson said she was opposed to all current basic rate taxpayers paying any more income tax, and asked if Ms Sturgeon was too.

Ms Sturgeon said it would be wrong to rule out options ahead of a debate.

She said the government would set rates “responsibly and with the interests of households, businesses, wider society and the economy firmly at heart” and “not simply transfer the burden of austerity on to the shoulders of those who can least afford it”.

She went on: “We know we face further Westminster austerity imposed by Ruth Davidson’s party. We know that we face the implications of Brexit, from which Ruth Davidson thinks that the country might never recover, and a range of other pressures, such as demographic[s].

“If we want - as I certainly do - this country to continue to have the highest quality public services, well-paid public servants, the support and the infrastructure that our businesses need to thrive, and effective policies to tackle poverty, we need to have an honest and mature debate about how best to deliver those things.”

Ms Davidson replied: “I think that anyone in Scotland who earns less than £43,000 a year just heard the First Minister’s message loud and clear - she is coming for their paycheck.”

The First Minister said she hoped Labour, the LibDems and Greens, who all backed tax rises in 2016, would engage in the debate with an open mind, but suspected the Tories would stick to demanding more spending while also calling for tax cuts for the rich.

She said that was “not a credible position”, adding: “That should hardly be surprising, as the Tories are increasingly not a credible party”.

Citing warnings from the Scottish Chambers of Commerce and Scottish Retail Consortium that tax hikes could squeeze consumer spending, Ms Davidson said: “Jacking up taxes on working families and businesses in Scotland will damage the Government's stated objective of getting the economy growing faster and of bringing in more revenue."

It could also damage Scotland's reputation as a place to do business, she said.

Ms Sturgeon said businesses also needed investment and infrastructure.

She said: “We will lead an open, honest, mature debate about how we, as a country, best provide the services and business support that we need.

“I do not know whether the Tories will want to be part of that debate or whether they will simply call for more spending and tax cuts for the richest.

“Nevertheless, I am determined to lead a debate that is right for the overall interests of this country of which I am proud to be the First Minister.”

After FMQs, Ms Sturgeon’s official spokesman repeatedly refused to say if the SNP manifesto promise on freezing the basic rate of tax still held, or could be abandoned.

Instead, he stressed the government was a minority one, reliant on other parties to pass its budget, and public finances were under strain because of austerity and Brexit.

“Budgets have to be on a consensual basis,” he said.

On Wednesday, Transport minister Humza Yousaf also ducked direct questions about sticking to the manifesto promise when questioned about it on ITV Border.

He said: “Let’s not get ahead of ourselves. This is a discussion paper on the income tax proposals, so we’ll look to see what other parties have said.

“Let’s have an honest discussion, let’s have a debate, let’s speak to other political parties to see what ideas they come forward with, and what we’ll do at the heart of that is make sure we protect the poorest and the most vulnerable.”

Watch First Minister's Question Time