With more than half of Scotland's 59 seats declared, the Scottish National Party (SNP) has won nearly all seats, indicating a wipeout for Labour in its traditional stronghold north of the border.
Leader of Labour in Scotland Jim Murphy has lost his seat to the SNP's Kirsten Oswald in East Renfrewshire. Ms Oswald swept to victory with 23,564 votes to Mr Murphy's 19,295.
The nationalists have also seized the Kirkcaldy and Cowdenbeath constituency, which was once seen as Labour’s safest seat in the country, and which had been held by former prime minister Gordon Brown.
SNP candidate Roger Mullin won the seat from Labour’s Kenny Selbie. Mr Selbie polled 17,654 votes, nearly 10,000 fewer than Mr Mullin, who picked up 27,628 votes.
After the result was announced, a Labour source reportedly said: "Results in Scotland clearly very difficult - if exit poll right, the seats SNP taking off Labour will turn out to be crucial if David Cameron ends up back in No 10. Next government will have huge task uniting country."
Labour’s shadow Scottish secretary Margaret Curran lost her Glasgow East seat to the nationalists, who appear on track to pick up all seven constituencies in the city.
In Paisley and Renfrewshire South, Labour election campaign chief Douglas Alexander has been defeated by 20-year-old SNP candidate Mhairi Black.
Ms Black won with a massive 27 per cent swing from Labour to the SNP. Mr Alexander, who had held the seat since 1997, picked up 17,864 votes.
Liberal Democrats have also suffered, with employment minister Jo Swinson being defeated by the SNP candidate John Nicolson in East Dunbartonshire. Ms Swinson had held the seat since 2005.
Former party leader Charles Kennedy lost his seat to SNP candidate Ian Blackford in the Ross, Skye and Lochaber constituency.
Meanwhile, Kilmarnock and Loudoun has elected the SNP’s Alan Brown as MP, with 30,000 votes.
The seat had been in Labour’s hands for the past 18 years. Mr Brown defeated shadow economic secretary Cathy Jamieson, gaining almost double the number of her votes.
The Kilmarnock and Loudoun result represents a 26 per cent swing from Labour to the SNP.
The SNP also picked up the second Scottish seat to declare, the Western Isles, which Angus MacNeil held with a majority of 4,102.
He won 8,662 votes, with Alasdair Morrison for Labour coming in second on 4,560.
The SNP also gained from Labour in Motherwell and Wishaw, with nationalist Marion Fellows defeating Frank Roy by 27,275 votes to 15,377.
Sturgeon statement
SNP leader Nicola Sturgeon arrived at the Glasgow count to cheers from party activists and supporters.
She told reporters: “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 an 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.”
Exit poll
Ms Sturgeon earlier said an exit poll showing her party winning 58 of Scotland’s 59 seats in the UK’s general election should be treated with huge caution.
“I’d treat the exit poll with HUGE caution,” the leader of the Scottish National Party (SNP) tweeted. “I’m hoping for a good night but I think 58 seats is unlikely!”
The SNP, which lost last year’s referendum on Scottish independence, seems to have capitalised on a surge in support and membership following the vote, according to the survey of voters published after polling stations closed in today’s election.
Prior to the election, the party had six seats in the House of Commons. Its best previous result was 11 in 1974.
The exit poll shows prime minister David Cameron’s Conservatives are on course to win the most seats in the UK parliament, with 316 seats, which would be just shy of an outright majority.
The poll put the main opposition party Labour at 239 seats.
A YouGov poll in Scotland for The Times in the UK earlier showed Nicola Sturgeon's party - with which Labour leader Ed Miliband has ruled out any formal deal - enjoying 48 per cent of support, to Labour's 28 per cent, putting several key figures in peril of losing their seats.
Ms Sturgeon had said her party was “within touching distance” of winning a majority of Scottish seats at Westminster for the first time and being able to make sure “the voice of Scotland is going to be heard more loudly at Westminster than it has ever been heard before”.
She had appealed to Labour to join forces to “lock out” the Conservatives but warned that her MPs would vote down a future Labour budget if it failed to end “Tory austerity” - a threat that has been seized on by the Tories as a central theme of its campaign.
Electoral fraud
Meanwhile, police in Glasgow have been alerted to a possible fraudulent vote.
Scottish police are investigating suspicions that someone entered a polling station in the Glasgow East constituency and crossed a ballot paper under another person’s name.
The presiding officer informed authorities earlier today and counting staff will be on the lookout for the paper in question when the box arrives at the Emirates Arena count.
They will wear blue gloves to locate the paper, which will be counted and sealed in a bag before being handed to police, Glasgow City Council said.
Agencies