SNP ministers should apologise to voters for breaking their promises on tax, Ruth Davidson said yesterday, as she confronted them with a series of election pledges not to raise bills.

The Scottish Conservative leader said people had been “misled” by repeated assurances that the basic 20p rate of income tax would be frozen until 2021.

The pledge was included in the SNP manifesto for last year’s Holyrood elections.

All the parties at Holyrood bar the Tories are currently in talks about making the income tax system more “progressive” in order to raise more money next year for public services.

Nicola Sturgeon recently launched a discussion paper on how more could be raised by adding bands and changing rates, with higher bills likely for those earning over £31,000.

Standing in for Ms Sturgeon at First Minister’s Questions, her deputy John Swinney said the Tory plan was to cut tax for the highest earners, draining £140m from the public purse.

He said the SNP would “stand shoulder-to-shoulder with low income households in Scotland and take the right decisions to protect their incomes”.

However he acknowledged the Government faced making some "real hard decisions".

It followed a sustained attack from Ms Davidson, who said the SNP had wheeled out “honest John” to tell people taxes wouldn’t go up, but then those promises “turned to dust”.

She reminded Mr Swinney that before the election he said a "tax rise would be a punishment" for low income workers.

She said: "Can the Deputy First Minister explain why the SNP said one thing to people about taxes when they needed their votes, and another once they had them?"

She also reminded him that a month before the election, Mr Swinney "promised that basic rate taxpayers would not see their tax bills rise", something he described at the time as “the right reassurance to give people who are already finding it challenging to make ends meet”.

The pledge was a “reassurance for the remainder of the parliamentary term”, he had said.

Ms Davidson went on: “It sounds to me like the Deputy First Minister isn't prepared to stick to that promise. Just a few weeks before the election he said this: 'I want to say to teachers and public service workers the length and breadth of the country, I value the sacrifices they have made and the last thing I am going to do is put up their taxes'.

"The last thing? It turns out the only thing you lot are going to do with taxes is put them up."

She accused the SNP of saying "one thing before an election, the exact opposite after" and ask Mr Swinney if his was an "honest government".

The deputy FM sad the Government was having a “substantive debate” with the public about the choices faced in government suffering from Tory-led austerity at Westminster.

He reminded Ms Davidson that the Scottish Government had spent tens of millions mitigating Tory welfare reforms such as the bedroom tax.

Mr Swinney also informed MSPs that Ms Sturgeon had returned early from the UN climate change conference in Bonn to be available for talks on the crisis-hit BiFab yards.

He said the Government was doing “absolutely everything" possible to protect hundreds of jobs at the company’s sites in Burntisland, Methil and Arnish.

Ministers had held discussions with all parties involved in the "private contractual dispute" which led the company to warn it is in danger of going into administration, he said.

The firm, which makes equipment for the oil, gas and renewable energy sectors, has a workforce of 1,400 employees, contractors and subcontractors in Fife and Isle of Lewis.

Green Patrick Harvie said if the government could but Prestwick Airport it could surely commit to and invest in a renewable industry manufacturer.

Labour’s Jackie Baillie said: “It is essential that all options are explored."

Willie Rennie claimed Scotland’s reputation has been damaged by Alex Salmond’s decision to host a chat show on the “Kremlin-backed propaganda” channel RT.

The Scottish Liberal Democrat leader said “it should turn our stomach to know that a former First Minister of this country is giving it credibility and legitimacy by launching this show”.

Earlier, Estonian diplomat Tiina Intelmann told a Holyrood committee: “We have a view about Russia Today as an arm of Kremlin propaganda – that’s exactly what it is”

Mr Rennie also questioned whether Mr Salmond was a “fit and proper person” to take over Johnson Press, publishers of the Scotsman.

He is currently part of a takeover bid that would see him become the group‘s chair.

Mr Swinney said there was a “stinking reek of hypocrisy” about the debate over Mr Salmond and RT, and pointed out LibDem leader Vince Cable appeared the channel in 2015.

Mr Salmond was “not currently an elected politician” and defended the “plurality of choice” of guests on the programme so far.