Labour has called for the resignation of an SNP General Election candidate who used Twitter to post offensive messages.

Leader Jim Murphy said Neil Hay, standing in Edinburgh South, is not fit to be a candidate and his deputy Kezia Dugdale urged SNP leader Nicola Sturgeon to show some leadership and sack him.

Mr Hay apologised after he was unmasked as the user of the Twitter name "Paco McSheepie" and used it to describe unionists as "quislings" - a word which originates from the name of a wartime Nazi collaborator - and mock elderly voters.

Speaking at a rally in Edinburgh, Mr Murphy said: "I know it would be an unusual step to take but the SNP should sack this candidate. He's not fit to be a candidate.

"I know we're past the deadline for nominations but someone with these views - their name doesn't belong on the ballot paper and they don't belong to any sensible mainstream party.

"This isn't just about cybernatery, I get that cybernat stuff each and every day.

"But this is a candidate that, according to the polls, was ahead by a couple of per cent at the weekend.

"This man isn't fit to be a candidate and he isn't fit to be an MP."

Speaking at First Minister's Questions, Ms Dugdale said: "In recent weeks the First Minister has had to apologise to victims of online abuse from her supporters.

"Rather than simply empathising with the victims, she needs to show some leadership and take on the perpetrators. That starts with the sacking of Neil Hay."

Scottish Conservative candidate for Edinburgh South, Miles Briggs said: "Questions clearly must be asked if he is fit to serve in public office.

"Nicola Sturgeon has said she will not tolerate this sort of language and attacks on Scots - it's time she proved that."

Mr Hay said: "The words in these old tweets were poorly chosen and I apologise for any offence caused. They are not in keeping with the way I would express myself now.

"To make it clear that I and the way I express myself have moved on - I hope and believe for the better - I deleted this Twitter account and only use my own campaign account."

At First Minister's Questions, Ms Sturgeon said a senior Labour activist, Ian Smart, had also been abusive, describing the SNP as "fascist scum".

She said: "I do condemn the language used and I condemn the comments made, as I always do when anybody steps out of line on Twitter, Facebook or any medium.

"Neil Hay has rightly apologised. I think given that we face a General Election two weeks today, it is now up to the voters to decide."