SCOTLAND’S three biggest political parties are failing to come clean with Scots in their manifestos, a think tank has claimed.

The Institute for Fiscal Studies (IFS) says the SNP, Labour and the Tories all underestimate how hard it will be to pay for their pre-election commitments and are failing to level with voters on the scale of the challenge.

It found Scottish Government's budget is likely to be tight in certain areas from next year, even before the parties' new spending plans are accounted for.

David Phillips, associate director at the IFS, said: "The SNP and Scottish Labour envisage what they might think of as a Scandinavian-style future – with a smorgasbord of new entitlements for Scottish residents.

"In contrast, the Scottish Conservatives' public services and benefits offer, while an increase on what is there today, is less expansive with an aim instead of modestly reducing tax.

"Another thing these manifestos have in common is, unfortunately, a disconnect from the fiscal reality the next Scottish Government is likely to face.

"Rising demand for, and costs of, health and social care could easily absorb three-quarters of the projected cash increase in the Scottish Government's budget over the next few years, substantially more than the SNP and Conservatives have budgeted for."

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In an online discussion, Phillips said the Conservatives' plan for a "double lock" on NHS spending was effectively promising the same Barnett consequentials twice.

He said the Scottish Government's overall budget was projected to increase by about £4.9bn over the next four years.

However, increased costs for the NHS and social care are predicted to absorb 75% of this, making spending promises elsewhere more difficult.

Phillips commented: "Scotland's politicians have really failed to level with voters on the challenges that lie ahead."

He explained: "Scottish Labour have not even set out NHS spending plans beyond this year but it is hard to imagine them spending less given their plans for a £15-an-hour minimum wage for care workers by the end of the parliament.

"Paying for the billions in additional pledges in these manifestos would therefore mean either increases in Scottish taxes or cuts to some other areas of spending, unless substantially more UK government funding is forthcoming.

"It is also disappointing that, with the exception of the Scottish Conservatives, there is no serious attempt by the parties to provide transparent and comprehensive costings for their plans.”

The IFS said only SNP, Labour and Tory manifestos were analysed due to time and resource constraints.