The SNP has been accused of failing to set out how it will continue to pay for tax-funded universal services.

The party had been challenged to explain by the end of 2012 how policies such as free NHS prescriptions can be funded over the next decade.

Conservative finance spokesman Gavin Brown called for Finance Secretary John Swinney to publish the details during a heated Holyrood debate on public service provision on October 3.

The issue shot up the political agenda when Labour leader Johann Lamont used a speech one week earlier to criticise a "something for nothing" society, casting into doubt her party's support for free university tuition fees, the council tax freeze and free prescriptions.

She has since gone further by suggesting last month that students should pay a modest contribution towards their education.

The graduate endowment saw students under the previous Labour-Liberal Democrat coalition at Holyrood pay money towards their education after they graduated. It was scrapped by the SNP, describing it as "back end tuition fees".

Mr Brown said the Finance Secretary should be able to set out a 10-year plan so the substantial issues linked to an ageing population and squeezed public finances could be discussed properly. He said: "Scotland is facing a demographic timebomb, yet the SNP seems determined to provide free prescriptions and travel to those who can well afford it."

A Scottish Government spokesman said: "The Scottish Government has delivered a balanced budget in every single year and still protected the council tax freeze, free university education, free prescriptions and bus passes for our oldest citizens."