SCOTLAND’S only Labour MP is facing the loss of his seat under boundary changes which also threaten to drag a series of high-profile Nationalists into messy selection battles.

Ian Murray, whose Edinburgh South seat is split in two under Conservative plans to reduce the number of MPs from 650 to 600, denounced it as “unfair, undemocratic and unacceptable”.

The boundary proposals, which go out today for a 12-week consultation before a vote in parliament, were drawn up by the independent Boundary Commission for Scotland.

Read more: Kezia Dugdale's Labour facing council polls meltdown

The number of Scottish seats is set to fall from 59 to 53 by the 2020 general election, with the average electorate increasing from around 66,000 to 73,500 voters.

Only three seats survive the boundary review unscathed - East Lothian and the automatically protected island seats of Orkney & Shetland and Na h-Eileanan an Iar.

Scottish Secretary David Mundell also sees changes to his Dumfriesshire, Clydesdale and Tweeddale seat, which becomes Clydesdale and Eskdale, but these are relatively minor.

Mr Murray now faces a choice between chasing the worker class voters who deserted him in an expanded Edinburgh East seat, or sticking with the middle class tactical voters who helped him survive in 2015 in the new Edinburgh South West and Central seat.

If he turns east he faces the SNP’s Tommy Sheppard, if west Joanna Cherry QC. Handily for Mr Murray, Ms Cherry’s seat includes the Hearts FC ground, where he is a director.

Read more: Kezia Dugdale's Labour facing council polls meltdown

He said: “These Tory proposals to redraw constituency boundaries are unfair, undemocratic and unacceptable. They are based on an out-of-date version of the electoral register with nearly 2m voters across the UK missing.”

Because of its success in 2015, the party most affected by the proposals is the SNP.

Among the other seats effectively disappearing are Dundee East, East Dunbartonshire, Glasgow North, Inverness, Kirkcaldy & Cowdenbeath and Motherwell & Wishaw.

These are held respectively by former SNP deputy leader Stewart Hosie, SNP culture spokesman John Nicolson, former SNP National Secretary Patrick Grady, transport spokesman Drew Hendry, Treasury spokesman Roger Mullin and whip Marion Fellows.

Mr Nicolson now faces having to challenge Martin Docherty-Hughes for the new West Dunbartonshire & Bearsden North seat or Stuart C McDonald for Milngavie & Kirkintilloch.

The changes also pit Mr Grady against Carol Monaghan for Glasgow West; Drew Hendry against Ian Blackford for Inverness & Skye; and Ms Fellows against Angela Crawley for Hamilton & Motherwell.

However Mr Mullin is expected to retire, sparing the party one fight, as is Angus MP Mike Weir, who on paper would be Mr Hosie’s rival for the Angus Glens & Dundee East seat.

SNP Westminster leader Angus Robertson said cutting MP numbers was “unacceptable”.

Read more: Kezia Dugdale's Labour facing council polls meltdown

He said: “It is outrageous and undemocratic that the UK government is planning to cut the number of Scottish MPs while it continues to pack the unelected and unaccountable House of Lords with yet more Tory donors and cronies to do the government’s bidding.”

After the consultation, the final proposals are due to go to the UK government in 2018.

The boundary review was dropped in the last parliament after the LibDems refused to support the Conservative plans amid feuding within the Coalition.

Former First Minister Alex Salmond last week predicted the changes would never become law, as too many Tory MPs were worried about losing their seats to support them.

Constitution minister Chris Skidmore said the reforms would achieve "equal-sized constituencies that will ensure an equal say for each voter" as well as saving £66m over the next parliament.

The Boundary Commission for Scotland plans are available at