Nicola Sturgeon says the SNP would prop up a Labour government even if the Tories had a 40-seat lead

The Scottish First Minister told Newsnight she wanted an anti-Tory majority at Westminster

(PA)

The SNP would support a Labour government at Westminster even if Conservatives had 40 more seats than Ed Miliband’s party, Nicola Sturgeon has said.

The Scottish nationalist leader told BBC Newsnight that the Tories would need to secure a majority elsewhere in order to govern again and that she would not support David Cameron to become prime minister.

“Even if the Tories are the largest party, if there is an anti-Tory majority, my offer to Labour is to work together to keep the Tories out," the first minister told the programme.

Asked whether Mr Cameron’s party being larger than Labour by "10, 20, 30, 40" seats would affect her decision, she said: “Governments in the House of Commons are about who can command a majority.

“If there is an anti-Tory majority, yes... we would work with Labour to stop the Tories getting into Downing Street.”

Labour has ruled out a coalition with the SNP but has left the door open to a more informal supply and confident arrangement.

Neither Labour nor the Tories have ruled in or out a deal with the Liberal Democrats, who may still end up with a significant number of seats despite a collapsing vote share.

Current polls show the race between Labour and the Tories to be the largest party neck-and-neck with neither side currently likely to secure a majority on polling day.