ED Miliband was accused of “losing the plot entirely” after claiming the SNP were in an “unholy alliance” with the Conservative Party.

Speaking at a campaign event in Clydebank, the leader of the Labour Party responded to former First Minister Alex Salmond’s claims over the weekend that the SNP could have input regarding the budget of a future Labour minority government.

This was, according to Miliband, “Alex Salmond at it again”. He said: “I’ll tell you who’s going to be writing the Labour budget – it’ll be me and Ed Balls. It’s not going to be Alex Salmond. Not in a million years.”

He added: “There seems to be an unholy alliance between the Conservative party and the SNP to carry on a Tory government.”

But Miliband had “lost the plot”, according to the SNP deputy leader Stewart Hosie. “I do not understand for the life of me why Ed Miliband is saying these things,” he said.

The SNP have repeatedly ruled out any sort of post-election deal with the Conservatives. With several Liberal Democrat seats at risk in Scotland, SNP gains would actually leave David Cameron and his most likely coalition partners further from an overall majority in the Commons while Cameron’s Tories are unlikely to be affected.

Miliband, once again, emphasised that he would not enter into a coalition with the SNP. When asked if he would countenance a “confidence and supply” agreement, whereby SNP votes would keep Labour in power in return for some influence in policy, Miliband did not quite rule it out, but insisted that he was campaigning for a Labour majority.

“How other parties decide to vote on the basis of a Labour Queen’s speech is going to be up to them,” he said, “but I want a majority Labour government and ... what we’re going to try to do is show the people of Scotland what the choice is at the General Election. You don’t blow the whistle on a match before the game is over. I’m not going to do that.”

Miliband also denied one journalist’s claim that the election was being seen as “referendum two”, adding: “I think it’s incredibly important that people see the election as what it is. The referendum was last year’s decision, the election is this year’s decision and it’s a very simple decision.”

The comments came as part of a question-and-answer session after a speech in which Miliband attempted to spell out the differences between Labour and the Conservative party. David Cameron’s Conservatives, he said, were a “rotten, unfair, discredited, Tory government”, with a Chancellor who was cutting, “not because he has to, but because he wants to.”

It was a speech focusing on the national fight between Labour and the Conservatives.

The difficulty for Miliband was that his speech coincided with the publication of an ICM poll for the Guardian showing that the party in Scotland have made negligible progress since Jim Murphy became leader.

The poll, taken between March 13 and 19, put the SNP at 43 per cent and Labour on 27 per cent – up just one per cent since December. The Conservatives polled 14 per cent, UKIP were on 7 per cent, the Lib Dems on 6 per cent and the Greens on 3 per cent.

The poll found First Minister Nicola Sturgeon had a net positive rating of plus 21, Jim Murphy held a net negative rating of minus two, while Ed Miliband’s rating stood at minus 39.

Analysis of the poll by Professor John Curtice suggested Labour could be reduced to just two seats – Glasgow North East and East Dunbartonshire.

Speaking to the BBC after Miliband’s speech, Hosie added: “What we know is, in Scotland an SNP-Labour arrangement is the most popular. But you have to vote SNP to get that.

“If there’s a majority of SNP and Labour MPs that can stop a Tory government then Ed Miliband would be very, very foolish indeed to rule out any sort of arrangement that could deliver that.

“He doesn’t want to be the handmaiden of another Tory government by refusing to talk to the SNP.”