Nicola Sturgeon has said people across the UK will not forgive Ed Miliband if he turns down the chance to lock the Tories out of Downing Street.

During last night's television debate, the Labour leader rejected calls from the First Minister to work with the SNP to prevent David Cameron from returning to power.

Ms Sturgeon was back on the campaign trail in her hometown of Irvine in Ayrshire today, where she was congratulated on her performance in the showdown, which also featured Ukip leader Nigel Farage, and her Plaid Cymru and Green allies, Leanne Wood and Natalie Bennett.

"Ed Miliband knows as well as I know that if there is an anti-Tory majority in the House of Commons after the election then the only way David Cameron gets back into Downing Street is if Ed Miliband stands back and lets him back into Downing Street," she said.

"If Ed Miliband and Labour do that, they will not be forgiven, certainly in Scotland and I suspect in large parts of the UK as well."

She added: "It was very clear last night that on its own, Labour is not going to be bold enough to offer a real alternative to the Tories.

"That's why SNP MPs are so important, so we can hold Labour to account, keep Labour honest and make Labour bolder than it will be on its own."

Ms Sturgeon's comments came as Scottish Labour prepared to launch its manifesto in Glasgow.

The party is trailing the SNP in the polls, and Mr Miliband has already ruled out governing in a formal coalition with the nationalists after the May 7 vote.

The SNP has ruled out any deal with the Conservatives but said they would be prepared to support Labour on a vote-by-vote basis.

David Cameron has pressed Mr Miliband to rule out co-operating with the SNP on an informal basis.

Mr Cameron said in a Twitter message to voters: ''Ed Miliband won't rule out a vote-by-vote deal with the SNP so he can be PM. It would mean more borrowing and more taxes and you would pay.''

Ms Sturgeon was joined in Irvine by Central Ayrshire candidate Dr Philippa Whitford, an NHS consultant.

The SNP leader restated the SNP's commitment to voting to "restore" the NHS in England.

She has said SNP MPs at Westminster would be prepared to vote on "English only" issues such as health, arguing that any privatisation of the NHS in England has a knock on effect on Scotland's budget.

She said: "SNP MPs in the House of Commons will vote to protect the National Health Service and we'll vote against any further privatisation in England and we'll vote for proposals to restore the NHS in England to a full public service.

"We believe that the NHS should be a public service but secondly, privatisation in England threatens Scotland's budget so SNP MPs will vote to protect Scotland's budget."

Jackson Carlaw of the Scottish Conservatives warned that "chaos" would ensue at Westminster in the event of a Labour and SNP deal.

He unveiled the Tories' latest campaign poster in Edinburgh, which states that "the SNP and Labour want to bankrupt and break up the country".

Mr Carlaw said: "We saw what happened last night, exactly what we would get if the SNP and Labour got into power.

"If Ed can't stand up to Nicola in a TV debate, what chance has he got in standing up to her in Government?

"Last night he looked like an awkward teenager on a date with a strong-willed woman.

"We'd have an alliance between the party which wants to break up the country and the party which wants to bankrupt the country. People in Scotland can only avoid that by voting Scottish Conservative."