NICOLA Sturgeon has opened up the prospect of a bitter constitutional row after the election after she claimed a Conservative-led government relying solely on MPs from England for support would not be legitimate.

The First Minister said it would not be acceptable for the UK to be government by "the largest party in England" if the votes of Scots were not required to support it.

Her comments were angrily dismissed by the Tories and the Lib Dems, who accused her "arrogance" and of disregarding the UK's parliamentary system.

Speaking at an SNP rally in Dumfries last night, the First Minister said Scotland had frequently had to "put up" with Conservative governments elected on the back of votes in England.

Looking ahead to Thursday's too-close-to-call poll, she told supporters: "Surely a test of legitimacy that should be applied to whatever Westminster government is formed after this election cannot simply be that it is the largest party in England.

"The test that must be applied is whether a government can build a majority and win support that reflects the whole of the UK.

"English MPs will always be the largest part of any Westminster majority, but to ignore Scottish voices would be wrong."

She said it would be "more balanced" to have an alliance of parties representing the whole of the UK in power after Thursday than "a party trying to take power without UK wide support".

Her comments follow claims by senior Conservatives that a Labour government would be illegitimate if Ed Miliband's party came second in the election but formed a government thanks to SNP votes.

A spokesman for the Scottish Conservatives said: "Voters are electing 650 members of the UK Parliament on Thursday.

"Whoever can command a majority of those members in the House of Commons will be able to form a government regardless of whether they come from Scotland, England, Wales or Northern Ireland.

"Nobody is being ignored - this is the parliamentary system."

He said the SNP offered an alternative during the independence referendum last year, which was rejected.

The spokesman added: "The issue was settled then - it is a pity that Nicola Sturgeon is once again seeking to stir resentment and grievance."

Willie Rennie, the Scottish Lib Dem leader, said: "This shows a high degree of arrogance and conceit that the SNP believe they have won the election already before the polls have even opened."

Ms Sturgeon continued her helicopter tour of Scotland, starting the day in Fife and visiting Largs and Greenock before ending with a rally in Dumfries.

She condemned as "disgraceful" a protest by hardline nationalists who targeted a Labour street rally in Glasgow.

Scuffles broke out as Jim Murphy and comedian Eddie Izzard tried to campaign in the city centre.

In her speech to supporters, Ms Sturgeon repeated her pledge to vote against a Conservative Queen's Speech in an attempt to prevent David Cameron becoming Prime Minister.

But she added: "Let me also say this - Labour should not take our cast iron commitment to keep the Tories out as a free pass for them.

A strong group of SNP MPs will not let Labour simply be a paler version of the Tories - we will challenge them to become a better version of the Labour Party."

Giving a number of examples, she said she would press for a minimum wage of £8.70 per hour, higher than Labour's plan for an £8 rate.