Election 2015: SNP will demand separate agreement on halting Trident nuclear upgrade programme if it agrees to back Labour

Any SNP “agreement” with Labour that would put Ed Miliband in Downing Street will require a separate deal that the “renewal of Trident would not proceed,” the leader of the Scottish Nationalists has claimed.

In an apparent flip-flop of the SNP’s position on the UK’s nuclear deterrent, where Nicola Sturgeon has previously stated that her party could back Labour without a conditional promise to scrap the £30 billion nuclear upgrade programme, she told the BBC that Trident remained a “red line” issue.

She said: “Under no circumstances would we ever vote for the renewal of Trident or the spending of money on Trident. In terms of any formal arrangement with Labour – and I can’t make it clearer – Trident is a red line.”

A new poll, taken in the 40 Scottish constituencies won by Labour at the last general election, shows those supporting an independent Scotland favour the SNP doing a deal with Labour at Westminster.

The ITV News poll, conducted by ComRes, reveals a 19-point swing from Labour to the nationalists. This would mean the SNP taking 28 former Labour seats, many of them in West of Scotland - the so-called Labour “heartlands”.

Ed Miliband is predicted to be left with just a dozen Scottish MPs after 7 May.

The poll also indicates the continuing influence of last year’s referendum, with 56 per cent of those intending to vote SNP identifying “independence” as their priority.

UK-wide polls are continuing to forecast that without some formal arrangement with the SNP, Labour are unlikely to form the next government.

Although Labour remain committed to Britain’s Trident nuclear fleet, Mr Miliband has not confirmed that his party would be seeking a like-for-like replacement of the current generation of the four-vessel nuclear fleet.

Last week in her key-note speech to the nationalists’ largest-ever conference in Glasgow, Ms Sturgeon told delegates: “We will stand firm and unwavering against a single brass penny – let alone £100bn – being spent on the obscene status symbol that is a new generation of Trident nuclear weapons.”

Earlier this month the SNP appeared to soften its hard-line stance on Trident, saying it could support Labour on an issue-by-issue basis, without Trident being included in any deal with Mr Miliband.

Last year Ms Sturgeon said there were three conditions for a Labour deal: “real powers” for the Scottish Parliament, an end to austerity, and the removal of Trident from the Faslane base on the Clyde. She labelled the demands “loud a clear” conditions.

The SNP leader claimed there was support for scrapping Trident among Labour backbenchers and from many of its supporters in Scotland.

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