Ed Miliband has explicitly ruled out allowing another Scottish independence referendum, as he bids to ease voters' concerns about the prospect of any future SNP-Labour alliance. The Labour leader said a second independence poll 'ain't going to happen' even if he becomes Prime Minister with the support of SNP MPs next month. Mr Miliband's intervention came as the former prime minister John Major warned that the SNP was 'merely waiting for a good excuse to put separation back on the agenda'. Labour leader Ed Miliband, interviewed on the BBC this morning, explicitly ruled out allowing another Scottish independence referendum . Mr Major said the SNP would break their pledge not to hold another referendum 'for a generation'. He said the SNP were 'determined to prise apart the United Kingdom'. Former foreign secretary William Hague added that SNP could be 'calling the tune' if Ed Miliband became PM on the back of SNP support. He said this would mean: 'The people who want to break up the United Kingdom will be running the United Kingdom.' But Mr Miliband this morning accused the Tories of 'threatening the integrity of the United Kingdom' by talking up the prospects of Scottish nationalists in the May 7 General Election. The Labour leader insisted there would be no coalition with the SNP and flatly ruled out holding another referendum. He told BBC1's Breakfast that he had 'fundamental differences' with the SNP – including on a second independence referendum within five years. He said, adding: 'I'm not having that.' The Labour leader said a second independence poll 'ain't going to happen' even if he becomes Prime Minister with the support of SNP MPs next month . Labour party leader Mr Miliband addresses an audience during a campaign stop in Manchester this morning . Mr Miliband said Mr Cameron had been 'talking up' the SNP in the hope that it would take votes and seats from Labour north of the border and allow him to 'crawl back' into 10 Downing Street. 'I think David Cameron is playing fast and loose with the United Kingdom,' said the Labour leader. 'This is somebody who has given up hope of winning a majority. He is trying to boost the SNP. 'I think David Cameron is now threatening the integrity of the UK with the games he is playing. And I think Conservatives are now ashamed of what he is doing.' Mr Miliband cited Conservative former Cabinet minister Lord Forsyth who has warned that the party's tactic of targeting a Labour-SNP link-up was 'short-term and dangerous' and could ultimately damage the Union. In a BBC interview last night, the Labour leader insisted he would not be dictated to by the nationalists, even if he had to govern without an overall majority in the new parliament. But Sir John Major said that, in practice, Mr Miliband would be forced to accede to the SNP's demands or face the collapse of his government. 'If Labour were to accept an offer of support from the SNP, it could put the country on course to a government held to ransom on a vote-by-vote basis,' he said. Mr Miliband's intervention came as the former prime minister John Major warned that the SNP was 'merely waiting for a good excuse to put separation back on the agenda' Sir John added: 'Labour would be in hock to a party that - slowly but surely - will push them ever further to the left. And who would pay the price for this? We all would. We would all pay for the SNP's ransom in our daily lives - through higher taxes, fewer jobs, and more and more debt. 'This is a recipe for mayhem. At the very moment our country needs a strong and stable government, we risk a weak and unstable one - pushed to the left by its allies, and open to a daily dose of political blackmail.' The former premier pointed to the way that Scottish Labour leader Jim Murphy has already suggested that funds raised from the party's planned 'mansion tax' in England could go to Scotland. 'If a Labour leader asks for that, how much more will the SNP demand?' Sir John is expected to say. 'And if this is the way Labour intends to behave towards England, how can they say no to the SNP? And if Labour did say no, the SNP could withdraw support and bring down the government at any time.' SNP leader Nicola Sturgeon addressed the Scottish Trade Union Congress during a campaign visit to in Ayr this morning . MsSturgeon poses for a selfie with supporters during a campaign visit to in Ayr today, after launching the party's manifesto yesterday . With the opinion polls pointing to a hung parliament with the SNP holding the balance of power as the third largest party, the threat of a nationalist link-up with Labour has emerged as the main Conservative line of attack in the election campaign. The tactic has caused misgivings among some Tories. Lord Forsyth - who served as Scottish secretary in Sir John's government - warned that building up the SNP to undermine support for Labour in England could ultimately damage the Union. 'We've had the dilemma for Conservatives, which is they want to be the largest party at Westminster and therefore some see the fact that the nationalists are going to take seats in Scotland will be helpful,' he told the Guardian. 'But that is a short-term and dangerous view which threatens the integrity of our country.' He said Mr Cameron's call for 'English votes for English laws' in the aftermath of last year's Scottish independence referendum vote had 'shattered the unionist alliance against the break-up of the United Kingdom'. Labour MP David Lammy this morning admitted that the party would strike a deal with the SNP after the election . Meanwhile, former Labour minister and London mayoral contender David Lammy suggested that the party could 'do business' with the SNP after the election. 'I think we can win this election. But clearly, after the General Election, you would forge common alliance with parties that you can actually do business with and the SNP must be part of that story,' he told ITV News. 'I still think Labour can form the next government and that's what I am fighting for. But, yes, there is common ground with other parties and the SNP would be included in that and we may need to enter into discussion after the General Election.'
The Labour leader said he would not grant the SNP a second referendum . His remarks come amid growing warnings over an SNP-Labour alliance . John Major said the SNP were 'waiting for a good excuse' for a second poll .