A third former Labour MP has publicly said he will vote Conservative at the general election.
Tom Harris, a Labour MP in Glasgow for 14 years, said the prospect of Jeremy Corbyn as Prime Minister “just chills me to the bone”.
Mr Harris joins former Labour MPs Ian Austin and John Woodcock in saying they cannot support their former party in the election and instead will back the Conservatives.
The intervention came as Mr Corbyn arrived in Glasgow for a two-day visit to Scotland, and was seized on by the Scottish Conservatives who urged Labour supporters to "lend their votes" to stop a potential second independence referendum.
Mr Harris, who served as a junior minister under Tony Blair and Gordon Brown, said he didn't believe Mr Corbyn could be trusted with national security, and would "sell No voters out" for a deal with the SNP on a second independence vote.
The former Glasgow South MP who has been a campaigner for Leave in the EU referendum, spoke out as Mr Corbyn began a two-day campaign tour of Scotland. Mr Harris, who announced in 2018 that he had left the Labour Party, said Mr Corbyn "represents a kind of strain of left-wing politics that is a compete anathema to the traditional Labour Party".
He told BBC Radio Scotland's Good Morning Scotland programme: "He is not someone who can be trusted with the security of the nation as far as defence is concerned, he is a man who has instinctively sided with our country's enemies over the years he has been an MP.
"The idea of him becoming prime minister just chills me to the bone.
"The only way of stopping Corbyn becoming prime minister is to vote for Boris Johnson's Conservatives, it is a very simple, logical conclusion."
Mr Harris, who chaired the Scottish Vote Leave campaign in 2016, claimed security services in countries such as America and Australia "look at Jeremy Corbyn with great concern because they just don't feel this is a man that can be trusted with the fundamental responsibility of protecting the country - that is the first responsibility of any government".
He added: "I opposed him strongly even before he talked about him betraying the Scottish people and the Scottish Labour Party by allowing a second referendum, but yes, that does add to the many reasons to vote against the Labour Party."
He also insisted the only way Labour would "reform" and remove him as leader would be if it lost votes.
"The only way you will get reform in the Labour Party now, they only way they will come to their senses, is if they are seen to suffer the consequences of putting someone like Jeremy Corbyn at the head of their party."
Last week Ian Austin, the former MP for Dudley North who left the party over claims it had failed to do enough to tackle antisemitism in its ranks, said: “There’s only two people who are going to be prime minister on 13 December, Jeremy Corbyn or Boris Johnson. And I think Jeremy Corbyn is completely unfit to lead our country. Completely unfit to lead the Labour party.”
His views were echoed by John Woodcock, the former Barrow and Furness MP, who quit the party last year, saying a disciplinary case against him over claims of inappropriate text messages was rigged.
Woodcock said: “We have arrived in a campaign where one of two people are going to be prime minister. The choice to keep Jeremy Corbyn away from Downing Street, to stop him getting his hands on the levers of national security and defence, has to be to vote Conservative in this election, and that’s what I’ll be doing as well.”
Today Scottish Conservative MSP Annie Wells welcomed Mr Harris' remarks and said: “This is an important intervention from a highly respected former Labour MP.
“Labour voters don’t have to agree with everything the Scottish Conservatives do or say. But if they’re serious about keeping Scotland in the UK and finally moving on from a decade of chaos and division, there really is only one party for them.”
The SNP's Europe spokesperson Stephen Gethins, said Mr Harris comments - and those of former Tory minister David Gauke who has warned that a Tory majority could lead to a “disastrous” no-deal Brexit - made it "clear people across Scotland face the contrasting choice between the continued chaos of the broken Westminster parties, or the SNP's plans to escape Brexit and protect people's livelihoods.
“We know that there is no such thing as a good Brexit and that a no-deal crash-out would be devastating for Scotland’s economy, cost thousands of jobs, and harm people’s livelihoods.
“With the Tories intent on driving Scotland to the cliff-edge, and Labour’s Brexit stance as clear as mud, it is now all the more important that voters in Scotland back the SNP as the best placed party to deprive Boris Johnson of a majority, escape Brexit and put Scotland’s future into Scotland’s hands."