The SNP have hit out at Jeremy Corbyn after the Labour leadership frontrunner suggested Nicola Sturgeon’s party appealed to too many right-wing voters.

Mr Corbyn said that the SNP’s support was spread too widely across the political spectrum.

This “fundamental problem” placed a short shelf-life on the party’s current soaraway popularity, he suggested.

The SNP hit back saying that Mr Corbyn, a veteran left-winger who has emerged as the surprise leader in the Labour contest, should be more concerned with the reasons for his own party’s lack of electoral success.

Recent opinion polls suggest the SNP on course to easily win victory, and increase their majority, in next year’s Holyrood elections.

Earlier this week First Minister Nicola Sturgeon said she was not “quaking in the corner” at the thought of a new Labour leader at Westminster.

But Mr Corbyn, who spoke at four packed out rallies north of the border recently, said that many of those coming too listen too him in Scotland were SNP voters.

He told a Labour leadership hustings hosted by the Guardian newspaper that the Labour party in Scotland was going to have to “work very hard".

But, he added:“The SNP does have a fundamental problem. It is trying to span a political spectrum from the free market right to the political left, some of whom are former Labour people

“There are stresses and tensions there that at some point, maybe not immediately, will break.

“At that point many of the Labour traditions, the socialist traditions, that are so strong in Scotland will begin to assert themselves”.

An SNP spokesman said: ''The SNP's problems for Jeremy Corbyn appear to be that it is a popular, mass membership party that is focussed on fighting Westminster austerity and welfare cuts - Trident weapons of mass destruction dumped on the Clyde and the circus of patronage that is the House of Lords- in other word opposing the Tories.

"Maybe his colleagues could spend more time on the issues that people care about instead of sitting on their hands at Westminster and allowing the Tories to do their worst.''

Earlier this week Ms Sturgeon was asked about the Labour leadership contest when she appeared at the Edinburgh International Television Festival.

She said: "I'd struggle to vote for any of them

"Jeremy Corbyn at least has got people talking. He's got people inspired but that's not to say I agree with him on many things."

She said she was disappointed that the two women in the race, Yvette Cooper and Liz Kendall, had failed to "shine through".

Asked who she wanted to win, she said: "I'm not that bothered. I don't look at the Labour leadership contest and find myself quaking in the corner."

Meanwhile, Mr Corbyn has called for the Work and Pensions Secretary Iain Duncan Smith to resign.

It follows a row about the number of people who die shortly after they have been found fit to work in controversial sickness benefits tests