Labour faces meltdown in Glasgow with the party's traditional stronghold turning SNP yellow at the General Election, according to a new poll.

Senior Labour politicians like frontbenchers Douglas Alexander - who is the party's election campaign manager - Margaret Curran, Gregg McClymont and Cathy Jamieson would all lose their seats to the Nationalists, according to the latest snapshot from Tory peer Lord Ashcroft, who polled 16 Scottish seats, mainly Labour ones, some with large majorities and which either voted Yes to independence or where the result was close.

The overall swing to the Nationalist in Labour-held constituencies was more than 25 per cent. If repeated nationally Labour would lose all but six of its 41 seats.

The polling also showed Alex Salmond, the former First Minister, would easily win Gordon, and Liberal Democrat Chief Secretary to the Treasury, Danny Alexander, would lose his Inverness seat.

The survey looked at all the Glasgow seats and found only Glasgow North East would stay Labour with the current majority there falling from 54 points to just seven.

In the Labour-held seats, only 60 per cent of those who voted Labour in 2010 said they would do so again this year; some 35 per cent said they would support the SNP.

While the Conservative vote held up well in the polled seats, the Liberal Democrats' vote collapsed; only 12 per cent of the party's 2010 supporters said they would vote Lib Dem again; 47 per cent said they would switch to the SNP.

The single most popular election outcome in the surveyed seats was a Lab-SNP "coalition"; favoured by 39 per cent of voters overall, including 62 per cent of SNP supporters and 79 per cent of Labour-SNP switchers.

Lord Ashcroft, commenting on his polling, offered a health warning.

"As ever, it is vital to remember these polls are a snapshot, not a prediction. The Labour majorities in some of these seats are such that even a swing of this magnitude has not put the SNP far ahead; for example, just three points in Glasgow South West and Coatbridge, Chryston & Bellshill, and six points in Glasgow North West.

"With a vigorous Labour campaign there remains room for movement before May," he added.

Meantime, Angus Robertson, the SNP's election campaign director, said: "These polls include some of Labour's safest seats in the whole of the UK as well as Scotland and they are clearly excellent for the SNP. But we are taking absolutely nothing for granted and will work hard for every vote and seat in May."

The telephone poll undertaken between January 5 and 30 involved more than 16,000 people.

Jim Murphy, the Scottish Labour leader, acknowledged the poll showed his party was "well behind" and had a big gap to close but stressed "the only people who will benefit from these polls are David Cameron and the Tories".

He said: "It is a simple fact that the single biggest party gets to form the next government. The more seats the SNP get from Labour, the more likely it is the Tories will be the biggest party and David Cameron will get into government through the back door."

He added: "That would be a terrible outcome for Scotland but it's what might happen if Scotland votes SNP."