The SNP’s Holyrood manifesto will not include a commitment to hold an independence referendum in the next Parliament.

First Minister Nicola Sturgeon confirmed instead that the document, published on Wednesday, would back another vote only if there was “clear and sustained evidence” independence had the support of most Scots – or if there were a change of material circumstances, such as an exit from the European Union against Scotland’s wishes.

The manifesto will also offer new parents a free “baby box” of nappies, clothes and toys in an effort to drive down rates of infant poverty.

The initiative will be based on a highly successful Finnish scheme.

The SNP will also commit to a new, tougher target for reducing carbon emissions.

But Lib Dem leader Willie Rennie accused Ms Sturgeon of planning to spend the next five years "pouring over the runes to decide what constitutes a change in circumstances,while public services decline".

Meanwhile, a new report by Prof John Curtice from Strathclyde University has suggested that the ‘both votes SNP’ call could let unionist politicians in by the back door.

Prof Curtice said that predictions that the SNP could be so successful in the constituency vote for the Scottish Parliament had led to speculation that "that nationalist supporters might be wise on the second ballot to vote tactically for a different party, such as the Greens or the left-wing RISE grouping, both of which also support independence.

"That way their vote might contribute to the election of another independence-supporting MSP rather than apparently be wasted, though this is not a strategy without risks."

Today Labour leader Kezia Dugdale will announce that a Scottish Labour Government would establish Skills Scotland – a new agency to help workers.

All the parties will also battle it out over their environmental policies on Climate Day.

Ms Dugdale will highlight Labour's ban on fracking north of the Border and plans to tackle fuel poverty and cancel the SNP's cuts to air passenger duty, which Labour says will lead to an annual increase in greenhouse gas emissions of 50,000 tonnes.

The Tories will also accuse the SNP of "burying bad news" in a bid to avoid fresh questions over its housebuying tax.

The Scottish Conservatives said that the Scottish Government had failed to produce new figures last month for the sums collected by its Land and Buildings Transaction Tax.

The Tories say the revenues have fallen short of original estimates - leaving a multi-million pound black hole in Scotland's finances.

The SNP's failure to publish figures comes after it also failed to publicise its deal with two leading Chinese firms ahead of the election.

Scottish Conservative leader Ruth Davidson said: "The SNP's approach in this election campaign has been to bury bad news and spin its way back into office. It is the action of an arrogant governing party which has spent too long in power."

She also claimed that the Labour leader Jeremy Corbyn's "crackpot" economic policies were driving Scots towards her party.