FINANCE Secretary Derek Mackay has denied keeping MSPs in the dark and holding back a “slush fund” to buy off other parties to get next year’s budget through Holyrood.

Mr Mackay was accused of having “squirrelled away” a fortune and evaded parliamentary scrutiny, as he faced questions on how he found an extra £220m at the eleventh-hour.

The minority SNP government was only able to win the first vote on its Budget Bill last week after striking a deal with the Scottish Greens which involved an extra £160m for councils.

The agreement also involved the SNP dropping a manifesto promise to raise the threshold for the 40p rate of income tax in line with inflation from £43,000 to £43,430 in 2017-18.

Instead, the threshold will remain frozen at £43,000 in Scotland while going up to £45,000 in the rest of the UK, meaning Scots high earners paying £400 more than others in England.

The row over the behind-the-scenes deal coincided with the Scottish Government publishing the official “Scottish Rate Resolution” which defines the forthcoming tax rates and thresholds north of the border from April using newly devolved powers.

Ministers also confirmed the resolution would go to a vote of parliament on February 21.

Mr Mackay told the committee the extra £220m included underspends of £47.5m in resource funding, £42.5m in capital and £35m in financial transactions carried over from 2016-17.

Revised business rates income added another £60m, freezing the 40p tax threshold brought in £29m, and changes to borrowing had released a further £6m, he said.

Tory Murdo Fraser said it had been wrong to deny the figures to parliament in advance.

He told Mr Mackay: “It turns out you had down the back of the sofa the best part of £200m you weren't telling us about.

“How can it have been fair to Parliament and its committees, which were scrutinising your draft Budget and trying to carry out detailed and proper parliamentary scrutiny of that, when you had all this money squirrelled away that you weren't telling us about?"

He suggested the extra also meant there was "no need at all to create an income tax differential between Scotland and the rest of the UK".

Mr Mackay said he had worked hard to achieve a consensus in Parliament, and had ensured that “officials turned over every possible stone to find extra resources”.

But he added: "I didn't have resources waiting to be allocated. It was decisions that were able to be taken over the course of the last few weeks since the publication of the draft Budget [in mid-December]. My room for manoeuvre for future years is now somewhat limited."

Labour MSP James Kelly asked: “What do you think it says for the transparency of the Budget when effectively you've been sitting on a slush fund... and you hold that back for negotiations, therefore not being completely open with Parliament at the time of the draft Budget?"

Mr Mackay said that was “not an accurate, fair or reasonable characterisation of the Budget process", insisting her had been "prudent, constructive and transparent".

He said: “I totally refute any suggestion that I was sitting on any sort of fund ready to go.”

The committee later unanimously passed the Budget Bill at its second parliamentary stage.