Ed Miliband's refusal to work with the SNP to keep out a Tory government will be the final nail in Labour's coffin in Scotland, Nicola Sturgeon has said.

The First Minister said the Labour leader "has lost the plot" as she visited Dundee as part of a helicopter tour of key target seats.

Mr Miliband, who will campaign in Glasgow later today, last night made his strongest-worded declaration to date that he would not countenance any deal with the SNP in the event of a hung parliament after May 7.

During a special BBC Question Time programme, he said: "If the price of a Labour government is a coalition or a deal with the SNP, it is not going to happen."

Ms Sturgeon said the remarks would drive more voters to the SNP, during a visit which saw her greeted by dozens of activists on top of Dundee Law in the city, as well as SNP candidates for Dundee West Chris Law and Dundee East deputy SNP leader Stewart Hosie.

She said: "If Ed Miliband is really saying he would rather have a Tory government than work with the SNP for more progressive politics, then it's final proof that Labour has lost the plot.

"It will be the final nail in the coffin of Scottish Labour, and I suspect Labour in other parts of the UK, and it makes it all the more important that we have a big team of SNP MPs because we will need them to protect Scotland from the Tories because clearly Ed Miliband is not prepared to do it."

She added: "I think people across Scotland, and I suspect across other parts of the UK, will be appalled.

"If Ed Miliband is really saying that if there is an anti-Tory majority in the House of Commons and an opportunity to get the Tories out, he would stand back and watch David Cameron go back into Downing Street rather than work with the SNP, people in Scotland will never, ever forgive Labour if that turns out to be the case, and I suspect people in other parts of the UK won't forgive them either.

"I think Ed Miliband is saying these things because he's being bullied and bossed around by the Tories on this.

"I would have thought people who want to see an alternative to the Tories would rather see a Labour leader prepared to stand up to them.

"It's not a good sign when he's so easily bossed about by them."

With Labour facing a wipeout in Scotland, Mr Miliband will today urge Scots to reconnect with their Labour-supporting history.

Speaking ahead of his visit, Mr Miliband said: "Remember our great leaders, from Keir Hardie to Jennie Lee, John Smith to Donald Dewar. What would they want today?

"We could be on the verge of electing a Labour government. They would want to be part of it."

He added: "Nationalism never built a school. It never lifted people out of poverty. It never created a welfare state that healed the sick and protected our most vulnerable.

"It is Labour values, Labour ideas and the determination of people across Scotland that has built this country to what it is today."