General Election 2015: SNP in 'very strong' position to 'change direction' of next government, Nicola Sturgeon says

David Cameron branded the claims a 'frightening prospect'

Alex Salmond with Nicola Sturgeon in Gordon (PA)

Scottish nationalists would be in a “very, very strong” position to “change the direction” of the next government, SNP leader Nicola Sturgeon has said.

It prompted David Cameron to warn of the “frightening prospect” of a Labour minority government propped up by the SNP, who he claimed “wouldn’t care” about the rest of the UK.

With polls suggesting the SNP is set to win the vast bulk of Scotland’s 59 MPs – largely at the expense of Labour – the Ms Sturgeon’s party could be in a powerful position in the event of a hung Parliament.

However, speaking on the Andrew Marr Show, she insisted the SNP would play a positive and constructive role at Westminster and dismissed the suggestion her party would be a disruptive force.

Attempting to allay fears that the SNP would demand a second independence referendum in a post-election deal, Ms Sturgeon said a vote for the SNP in this election “is not a vote for independence, nor is it a vote for another referendum”.

But she refused to rule out the prospect of a referendum in the next Parliament, arguing it was “not democratic” for one politician to decide.

"I'm not planning another referendum,” she said. “Why do I fall short of categorically ruling it out? Because I don't think as a single politician I have got a right to do that.

"Whether there is another referendum, and whether Scotland becomes independent is not a matter for me to decide. It is a matter for the Scottish people to decide."

Appearing on the same show, Mr Cameron warned: "This would be the first time in our history that a group of nationalists from one part of our country would be involved in altering the direction of the government of our country and I think that is a frightening prospect.

"Frankly, this is a group of people that wouldn't care about what happened in the rest of the country. The rest of the UK - England, Wales, Northern Ireland - wouldn't get a look-in - that's the prospect we face if we don't get a Conservative majority government."

But Ms Sturgeon said the SNP had much in common with MPs representing English constituencies on the left of the Labour party and by working together, they could build a “progressive alliance” for people “right across the UK”.

"There is an opportunity to build progressive alliances for progressive policies. It is a real rather than a pretend alternative to austerity.

"I've got to persuade people that the SNP in the House of Commons after the election will not be any kind of disruptive force. We want to be constructive, to get better politics coming out of the Westminster system.

"As long as Scotland remains part of the Westminster system, it matters to people that we get good decisions out of that system, and I want the SNP to play a positive part in improving politics at Westminster for people right across the UK."

The latest Scotland-wide YouGov/Times survey shows the SNP on a record 49%, up three, with Labour trailing on 25%, down four. The Conservatives were on 18% and Liberal Democrats on 4%.

This was an all-time high for the SNP and also an all-time low for Labour in Scotland.

According to the website Electoral Calculus, if replicated at a general election as a uniform swing, the SNP would win 50 of the 59 seats in Scotland, with Scottish Labour left with a rump 9 MPs. The Liberal Democrats and Conservatives would be left with no MPs north of the border.

Last week a poll of marginal Scottish constituencies showed the SNP were set to topple senior Labour party figures, including the Scottish Labour leader Jim Murphy and the shadow foreign secretary and the party’s election campaign coordinator, Douglas Alexander.