Ed Miliband is still "clinging to the pretence" that he has a chance of winning an overall majority in the election, SNP leader Nicola Sturgeon has said.

The Scottish First Minister said her party was open to an arrangement with Labour and suggested many of its backbenchers would support certain SNP policies such as bringing an end to austerity and scrapping Trident.

The Labour leader has ruled out a formal coalition with the SNP after repeated calls for him to do so.

Ms Sturgeon said: "Of course he is going to say this.

"He is still clinging to the pretence he has got some chance of winning an overall majority.

"We have got vast experience as a minority Government ... the principles are the same. You have to build alliances, you have to win votes on a case-by-case basis.

"It would be far better than what usually happens to Scotland at Westminster, which is we are ignored or sidelined.

"The bottom line here is, if Scotland wants to have that influence, that power, that clout in Westminster, the only way get it is to vote SNP.

"If there is real SNP strength in the House of Commons we can force progressive change."

Asked whether Alex Salmond's claim that the SNP could lock the Tories out of government was arrogant, Ms Sturgeon replied: "If the Tories can't command a majority, then they don't deserve to be in government."

She also refused to comment on the date of a future independence referendum, saying that would not be influenced by the result of the May poll.

Ms Sturgeon told the BBC Radio 4 Today programme: "I don't know at this stage when there will be another referendum.

"These things will be determined by the people of Scotland in the normal way."

Labour campaign chief Douglas Alexander told BBC News channel: "The agenda of the Scottish National Party is very obvious - they want to drive down the vote of Labour in Scotland and they want to drive up the Tory vote.

"Why? Because (Ms Sturgeon) remains committed to independence. She judges the most propitious circumstances to be of a Tory government here in Westminster after the election in May, and after that to try to secure support in the 2016 election in Scotland for a second referendum.

"We should have no illusions. This is why she says she wants voters in England to vote Green. She's got an 'anyone but Labour' strategy. Nicola Sturgeon's not trying to help the Labour Party, she's trying to end the Labour Party. And in that sense, I would give no truck to the comments we've heard this morning."

Ms Sturgeon told BBC News: "In that post-election scenario, if the SNP wins the trust of people in Scotland and is there in numbers, then we've said very clearly there are no circumstances in which we would support a Conservative government. We would be open to a working arrangement with Labour - not a formal coalition, I've always said that's highly unlikely.

"That could be an arrangement that's akin to confidence and supply. If we were to have an arrangement on that basis, we've been very clear we would want an alternative to austerity - modest spending increases that still see debt and deficit reduce as a share of income, but nevertheless allow us to invest in things like innovation and infrastructure and protecting the vulnerable."

She said that a fresh independence referendum would not be the price for a post-election deal: "Voting SNP in the general election doesn't lead to another independence referendum.

"If there is to be another independence referendum - and I hope that one day there will be - that will only happen if people elect a Scottish Government in a Scottish Parliament election that has that in the manifesto and has the ability in the Scottish Parliament to pass that legislation."