Tory attempts to portray Ed Miliband in Alex Salmond's pocket are "fundamentally stupid" and ineffectual, according to Scotland's former first minister.

Mr Salmond told the SNP's spring conference in Glasgow that neither Labour nor the SNP were being harmed by Conservative attacks on the possibility of a post-election deal between the two parties.

He told around 3,000 delegates during a question and answer session at the conference that the party's MPs were already experienced in Westminster "skulduggery".

Mr Salmond said: "I think you should never, ever put your political opponents on your posters ... not because it's dreadful but because it's stupid.

"I think the Tory campaign is fundamentally stupid.

"I don't think it's doing Labour any harm and I don't think it's doing us any harm whatsoever because the most important thing for the SNP in every Westminster election is to achieve the thing we failed to achieve since 1974 and that's to achieve relevance in a Westminster election.

"And listen folks, nobody can say we are anything other than relevant to this election campaign."

Mr Salmond said current SNP MPs such as the party's Westminster leader Angus Robertson already have experience of "upsetting the apple cart".

He told the conference that he expected the number of SNP MPs elected on May 7 to be substantial, but that it was up to the Scottish people.

Mr Salmond said: "In terms of skulduggery and upsetting the apple cart and various parliamentary techniques, I think there's a wee bit of experience might be there in the group we have.

"I think there's a bit of background which will stand us in good stead, but make no mistake, if the SNP, as we did a generation ago, caused a fair amount of parliamentary interest when we were a group of four and five in a parliament of 650, then the very substantial group that we hope goes to Westminster from Scotland I think has an unprecedented opportunity to move politics in a direction of Scotland certainly but also, as Nicola (Sturgeon) has rightly pointed out, in the direction of progressive politics across these islands."

The former first minister admitted he had some regrets about how the Yes campaign played certain issues during the referendum campaign but insisted he took the "glass half full" approach to the outcome.

"We may have lost the referendum but we are substantially on our way to winning Scotland," he said.