The Scottish Government's commitment to providing free university education is now "writ in stane", Alex Salmond declared as he unveiled a monument to his administration's "biggest achievement".

A quote from the outgoing First Minister, illustrating the policy of providing students north of the border with free university education, has been engraved into a commemorative stone.

The words "The rocks will melt with the sun before I allow tuition fees to be imposed on Scottish students" have been carved into the monument, which has been installed at Edinburgh's Heriot-Watt University.

Mr Salmond - who made the comment in March 2011 - unveiled the monument before going to Holyrood to make his resignation statement, paving the way for new SNP leader Nicola Sturgeon to take over from him.

While students south of the border have to pay tuition fees of up to £9,000 a year for their studies, the SNP administration at Holyrood passed legislation to scrap the charges which students in Scotland had to pay on completion of their degrees.

Mr Salmond said: "The single biggest achievement by this Government has been the abolition of tuition fees. This one action has restored Scotland's long tradition of education being based on ability to learn - not the ability to pay.

"Scottish students can be assured this Government remains strongly committed to them and their futures - at a time when fees have soared to £9,000 a year in other parts of the UK, putting university out of reach for many without the means to pay.

"At the same time, we have boosted apprenticeship numbers to record levels, brought more women into the workforce and are outperforming the rest of the UK on job numbers as whole."

The stone was designed and carved by second year stone masonry apprentices from Historic Scotland's National Conservation Centre in Elgin.

Mr Salmond added: "It is both fitting and humbling to have this wonderful monument to that commitment created by young skilled apprentices - and to have the unveiling witnessed by students of today and children who will be the students of tomorrow.

"It is without doubt now a commitment writ in stane."

Apprentice stonemasons Gregor Alcorn, 26, and Ross Kennedy, 22, created the monument, which weighs 0.97 tonnes, from Clashach Sandstone, the same stone used in the building of the Museum of Scotland in Edinburgh.

Professor Steve Chapman, principal of Heriot-Watt University, said: "We are delighted to host this stone, a beautifully crafted piece and a monument to Alex Salmond's tenure as First Minister and his strongly held commitment to access to education for Scottish students."