Salmond's plans for childcare revolution come under scrutiny

But the First Minister insisted the "transformational" policy was only possible in an independent Scotland.

He said taxes from the increased employment it would generate would "disappear into the maw of the Treasury".

He told MSPs: "A childcare revolution is the sort of transformation under devolution that we can only imagine -with independence it's one that we can implement.

"The revenues would flow into the Scottish treasury after independence, which would enable that transformational plan to be funded."

The Scottish Government is in the process of passing legislation to provide 600 hours of free nursery care for all three and four-year-olds, honouring an election pledge dating back to 2007.

Under the SNP's independence plans, all three and four-year-olds would be entitled to 1140 hours annually, the same time children spend in primary school, by 2020. The policy would be expanded to include all children aged over one by 2024.

Yesterday, under pressure to explain how the £600 million cost would be met, Mr Salmond said the policy would be phased in using savings from defence and security spending.

In the longer term, the Scottish Government claims it would be self-financing, provided it increased the number of women in jobs by 6%, a target expected to boost tax revenues by £700m.

Mr Salmond - who is keen to increase support for independence among women voters - said families could save up to £4600 for each child receiving nursery care as a result of expanding free hours.

But Scottish Labour questioned whether the policy would succeed in attracting women into the workplace. Speaking after the debate, leader Johann Lamont said: "We welcome the First Minister's finally realising that childcare is a major issue but I am afraid he simply doesn't understand Scottish families and their lives.

"His latest figures only add up if you assume that everyone who takes up the childcare provision is currently not working."

She added: "We know the First Minister has a budget of more than £30 billion and we stand ready to work with him to act on improved childcare now rather than after the referendum.

"Alex Salmond's childcare offer is a testament to the hollowness of his case for independence, relying on offers he knows he can't deliver rather than a coherent argument for separation."

Willie Rennie, the Scottish LibDem leader who has campaigned for increased childcare provision, told MSPs: "If the First Minister can't even be trusted to match England on childcare, why should I believe a single word he says on childcare for 10 years' time?"

The childcare pledge was at the heart of the SNP's plans for the first years of an independent Scotland, as outlined in the White Paper.

Mr Salmond has promised a combination to get more women into work, increase immigration and cut taxes in a bid to grow the economy and tackle long-term financial pressures caused by an ageing population and falling oil revenues.

Mr Salmond insisted the blueprint was a guide to a "fairer, more prosperous and more democratic country" -and warned Scots faced the "severest cuts in political history" if they rejected independence.

In a symbolic vote, MSPs backed a motion by Mr Salmond welcoming the publication of the White Paper by 67 votes to 54.

Scottish Conservative leader Ruth Davidson MSP said later: "The SNP has had full powers to implement childcare reform at any time in the last six years.

"We have repeatedly called for improvements to childcare provision, but the Scottish Government has failed to deliver. Now, the SNP is in need of a referendum boost, the policy suddenly reappears.

"Until Alex Salmond provides the financial workings on how he will pay for his independence prospectus it will not be worth the paper it's written on."