Nicola Sturgeon has come under fire over support for students, with Labour claiming the "debt monster the SNP once promised to dump" is now a £2.7 billion debt mountain.

Scottish Labour leader Kezia Dugdale said the total value of student debt was now the Scottish Government's single biggest financial asset, amounting to more than the cost of building the new Forth Crossing and the flagship Queen Elizabeth University Hospital in Glasgow.

The First Minister insisted the package of support students in Scotland receive is the best anywhere in the UK.

She also pledged the SNP would not scrap bursaries for the poorest students, saying this was in "sharp contrast" to the Conservative government at Westminster.

Ms Sturgeon came under fire after the Student Awards Agency Scotland (SAAS) this week published figures which showed £64.9 million in bursaries and grants were awarded in 2013/14.

The Scottish Labour leader said: "Under the SNP government, the average student bursary or grant has been cut by almost 30% and it's the poorest students who are suffering."

Ms Sturgeon insisted: "We have the best support package for students in the whole of the UK. Those are not actually my words, they are the words of NUS (National Union of Students) Scotland.

"The number of students receiving support is higher than ever before and the average support provided is higher than it has ever been."

Ms Dugdale, Scottish Conservative leader Ruth Davidson and their Liberal Democrat counterpart Willie Rennie all quizzed Ms Sturgeon on the support students get at First Minister's Questions at Holyrood.

Ms Dugdale said: "When you look specifically at the student support for the poorest students in Scotland, that is the worst of all the four nations of the United Kingdom."

She pressed the First Minister on the total value of student debt in Scotland and when Ms Sturgeon did not give her a figure, she accused the SNP leader of being too ashamed to do so.

The Scottish Labour leader said: "I asked very specifically about student debt, I think on this occasion the First Minister did know the answer but she was too ashamed to say it out loud because the value of student debt in Scotland stands at £2.7 billion.

"The value of student debt is more than the combined cost of the new Forth Road Crossing and the Queen Elizabeth Hospital in Glasgow.

"In fact, the value of the accumulated debt of students is Scotland is now the government's single biggest financial asset, the debt monster the SNP once promised to dump is now a debt mountain."

The SNP had promised to get rid of student debt in the run-up to the 2007 elections at Holyrood but it is a pledge that remains unfulfilled.

Ms Dugdale demanded to know if the First Minister had ever had "any intention of keeping that promise".

The Labour leader kept up her attack, saying Ms Sturgeon had "told students that their debt would be zero".

But she claimed: "The reality is today it is easier to be poor and get to uni in England, even under the Tories, than it is in Scotland under the SNP."

As she was heckled by SNP MSPs, Ms Dugdale added: "I heard cries of 'shameful', yes it is shameful. She promised to abolish student debt, instead it has increased.

"She promised to expand grants, instead they have been cut. Isn't it the case that despite all the promises and all the moments of self-congratulation, the SNP government is letting down Scotland's poorest students?"

Ms Sturgeon responded by saying average levels of student debt were much lower in Scotland than the rest of the UK.

"When you look at average student loan debt, what you find is the figure for Scotland is significantly lower than any other part of the United Kingdom," she told MSPs.

"In England the figure is £21,180, in Wales it is £19,010 in Northern Ireland it is £18,160 and in Scotland it is £9,440. That is the reality."

Ms Sturgeon continued: "What Kezia Dugdale cannot escape is that average student loan debt in Scotland is significantly lower than anywhere else in the UK, and Scottish-domiciled students, and here I will talk about tuition fees, do not have to pay fees of up to £27,000 charged for tuition elsewhere in the UK.

"That is a real saving that doesn't become a debt in Scotland in the way it does in other parts of the UK.

"We have the best student support package in the UK, average student debt in Scotland is less than it is in any other part of the UK.

"We are taking steps to increase the bursary element of the total student support package and that stands in sharp contrast to what the UK Government is currently doing.

"Not content with tuition fees, the Chancellor announced in his budget statement that they are going to abolish bursaries altogether and move entirely to loan funding, something the Scottish Government will not do."

The First Minister added: "There's been a 50% increase since 2006 in applications to university from the 20% most deprived areas in our country, young people are more likely to participate in higher education by the time they're 30 than was the case in 2006.

"We live in tough financial times, everyone knows that, and tough choices always have to be made but we will continue to make sure we are providing good support for our students so that more of our students from the most deprived parts of our country can take the opportunity to go to university.

"So, we will continue to get on with the job and as usual we will leave Labour, regardless of what we do, to moan about it and whinge from the sidelines."

Ms Davidson said the First Minister had yet to present "a credible alternative plan on how we fund bursaries for poor students and ensure the wider access that we want".

The Conservative leader called for "all graduates who have enjoyed their university education to pay back a contribution once they got a decent job".

Ms Davidson said: "That money could then be used to help increase bursaries for poorer students who, under the current scheme, can't even get a foot through the door.

"That plan is sensible, it is moderate and it would help those most in need.

"What reason, other than an ideological one, would the First Minister have for not considering it?"

Ms Sturgeon told her: "Students who graduate and benefit from a university education pay back that through taxation.

"That is what I believe should happen, not to have tuition fees or a graduate tax or whatever terminology Ruth Davidson wants to use."

That led the Tory leader to accuse the SNP of having "written so-called free education on a tablet of stone".

Ms Davidson said: "I think it is sad that the First Minister is too stubborn to recognise the need for change because change is needed.

"Only one in ten of the poorest 18-year-olds are getting to university, but you are three-and-a-half times more likely to go if you are rich."

She urged the First Minister to "ditch the stone carvings and vanity projects, and move to practical solutions for our poorest students".

Ms Sturgeon said: "Ruth Davidson calls it ideological, I call it principle, it will be up to the people of Scotland to make up their minds."

Liberal Democrat leader Willie Rennie was mocked and jeered by SNP MSPs when he then criticised the party's policy on tuition fees.

The Lib Dems had to apologise after doing a u-turn on the issue of university fees while in coalition government with the Conservatives at Westminster.

Mr Rennie said: "For five years I have been lectured by the First Minister on student finance. All the while, her government was breaking its promise to dump the debt.

"It's not been dumped - it's been doubled."

Ms Sturgeon said: "Firstly, can I thank Willie Rennie from the very bottom of my heart, just a few months before the Scottish Parliament election, for so bravely reminding the Scottish electorate of the Liberal Democrats' record on tuition fees. That was, indeed, a most charitable thing to have done."