The SNP will pay a "political price" if they fail to protect spending on education, Scottish Labour leader Kezia Dugdale has warned.

During a debate at Holyrood, she called on her opponents to match her party's commitment to use new powers to raise income tax by 1p to invest £500 million in schools and other services.

Education Secretary Angela Constance insisted the tax policy would hit those on low incomes, stating it would be up to voters to judge the Scottish Government's approach to education at the ballot box in May.

The politicians clashed as they put forward conflicting claims over education spending and the effect of Labour's tax proposals.

Ms Dugdale insisted analysis by economists in the Scottish Parliament Information Centre showed that under the SNP's plans, more than £2.2 billion could be stripped from Scotland's public services in the next five years from areas they refuse to protect.

This includes a 16% cut to schools, she said.

Labour's tax policy had allowed her party to make a "very clear commitment to protect education spending in real terms over the next five years", Ms Dugdale said.

"There is a choice. Some of us can pay a little more or we can all get a lot less," she said.

"Time and time again I have heard the First Minister say that education is her number one priority.

"So, forgive me for saying that the hundreds of millions of pounds of cuts to schools and other public services is a funny way of showing it."

She added: "Our commitment to protect schools and other services by setting income tax at 1p higher than the rate set by George Osborne has now been looked at by the Scottish Parliament Information Centre, the IPPR, the University of Stirling, the Resolution Foundation and the House of Commons Library.

"All have concluded that, contrary to the First Minister's claim that this is regressive, this is progressive. It is fair and it is the only viable alternative to cutting education now."

Ms Constance said claims on the SNP administration's education spending were unsubstantiated.

"Funding for education has, in fact, increased by over 1% in cash terms. Further, the latest figures suggest that far from falling, education spending by councils is set to increase by 3.3% this year," she said.

On the tax plans, she added: "I won't be standing aside and allowing the low-paid to be punished even further.

"It is all very well making promises now, promises that they well know they will never get the chance to deliver. And, in my book, this is gesture politics of the very worst kind."

Conservative Mary Scanlon said: "This principle (Labour's call to protect education spending) is essentially ring-fencing and it does require a much wider debate and consideration."

Liberal Democrat Liam McArthur said his party backed protecting education with a 1p tax rise.

He said: "This is a progressive alternative to the cuts imposed by SNP ministers - cuts to schools which are anything but progressive."