Shadow chancellor John McDonnell has repeated his view that a Labour government would not block a second independence referendum.

The Labour politician doubled down on his controversial remarks on Tuesday in his second Fringe appearance in two days, saying preventing an independence vote would be walking into "a set-up by Nicola Sturgeon".

His latest comments come despite an angry backlash from a number of Labour figures north of the border, with Edinburgh South MP Ian Murray branding them "utterly irresponsible".

Scottish Labour leader Richard Leonard insists his party still opposes a fresh independence referendum, adding that he met with McDonnell on Wednesday morning to reiterate that view.

The First Minister, meanwhile, has welcomed the shadow chancellor's remarks as a "basic statement of democracy", criticising Scottish Labour's reaction as "inexplicable".

It follows a Lord Ashcroft poll at the start of the week which found, in the days after Boris Johnson's visit to Scotland, that support for independence had risen to 52%.

The survey also suggested a slender majority among Scots for holding a second referendum within the next two years - the timetable Sturgeon has outlined as her preferred choice.

Speaking at an Edinburgh Festival Fringe event with journalist Graham Spiers on Wednesday, McDonnell joked: "Boris Johnson visits for a couple of days and within hours support for independence rockets."

He was asked to clarify his earlier remarks on a second independence vote and pressed on if they amounted to a change of Labour policy.

The shadow chancellor said: "Our view is that another independence referendum is irrelevant, we've got to concentrate on the real issues facing people and yes, there will be a debate about the attitude of the UK Parliament and I've made my view clear on that.

"My view is exactly in line with Richard Leonard, which is we concentrate on the real issues, the independence referendum is a complete diversion.

"But I've also said continuously, I'm not being set up by Nicola Sturgeon to blame the UK Government for blocking the will of the Scottish people - that's too trite a political manoeuvre that's been taken on at the moment.

"In the situation we're in at the moment, my view is that we will not be blocking a proposal."

He added: "The best way forward in all of this is to elect a Labour government.

"We'll demonstrate what we can do and then I think the Scottish people won't be interested in another referendum.

"But if they ever do come back, my view is you can't be in a situation where you block it."

McDonnell's comments have provoked fury among several senior figures in the Scottish party after they ran on a manifesto in the 2017 general election against allowing Holyrood the Section 30 powers to hold a new independence referendum.

Speaking to STV News, the Scottish Labour leader said: "I met with John McDonnell this morning to make clear that not only does the Scottish Labour party oppose it, the people of Scotland do not want it.

"What we need to concentrate on inside the Labour party is the election of radical, reforming governments both at a UK level and in Scotland.

"The position of the Scottish Labour party is absolutely clear: we oppose a second independence referendum.

"We've just had one, and the one we just had was a once-in-a-generation referendum."

Leonard added: "In the end, a Labour government will be elected on a Labour manifesto and it's my view that the manifesto that we go into the next general election on will be categorical in saying that we will oppose a second independence referendum.

"That was the platform we stood on in 2017 and I am determined that will be the platform we'll stand on at the time of the next general election."

In the wake of the Ashcroft survey, which gave independence the lead for the first time in a major poll since March 2017, the First Minister was in Stirling on Wednesday to open a waste water energy hub.

She told STV: "John McDonnell's remarks were a statement of basic democracy.

"What he said, rightly in my view, is that is for the Scottish Parliament to determine the timing of an independence referendum and for the Scottish people to decide whether or not Scotland becomes independence.

"A Westminster government has every right to oppose and argue against independence but a Westminster government has no right to try to block the right of the Scottish people to decide."

Sturgeon added: "Scottish Labour's reaction to that seems to be an affront of democracy but also perhaps helps to explain why they're in the doldrums in the way they've been for some time."

She welcomed that the polling had "endorsed" her timetable for an independence vote, adding: "The essence of this argument is it's not for Boris Johnson, Jeremy Corbyn, John McDonnell, Nicola Sturgeon, to decide the future of Scotland, it's for the people of Scotland to decide their own future.

"I am confident - I have always been confident - that the people will get that right and no Westminster government will be able to block it."