Labour is predicted to be wiped out north of the border, and there have already been a number of high-profile casualties for the party.

The party's leader in Scotland, Jim Murphy, has lost his East Renfrewshire seat to the SNP, while general election campaign chief Douglas Alexander has also been ousted.

The shadow foreign secretary, who had held the seat since 1997, lost out to 20-year-old student Mhairi Black.

Labour also lost its safest seat in Scotland - Kirkcaldy - which had been held by former prime minister Gordon Brown.

Some constituencies are showing swings from Labour to the SNP of more than 30%.

The party won six seats in 2010, a total it has already surpassed easily.

Thirteen seats have been gained from Labour, while one has been taken from the Lib Dems.

Lib Dem UK business minister Jo Swinson lost her East Dunbartonshire seat which she had held since 2005 due to a 16% swing to the SNP.

The tone was set early on when Alan Brown won the SNP's first seat of the night with 30,000 votes.

He unseated Labour's Cathy Jamieson in Kilmarnock and Loudoun.

Speaking in Glasgow, Ms Sturgeon said: "I don't want David Cameron to be prime minister, I don't want another Tory government, and we've still got a long way to go tonight to see how the final results shape up across the UK.

"But my position remains as it was during the campaign, if the parliamentary arithmetic means there is a anti-Tory majority, the SNP stands ready and willing to work with Labour to lock David Cameron out of Downing Street.

"If that proves not to be the case because Labour failed to beat the Conservatives in England, then SNP MPs will go to Westminster to stand up for Scotland and to protect Scotland against a Tory government, but I still hope we can have a situation where we can lock David Cameron out of Downing Street."