The SNP Westminster leader said that Scotland had been "consistently sidelined" during the Brexit process, and as a result should be allowed to hold indyref2.

He added that Prime Minister Boris Johnson had "completely trampled over the devolution settlement" and people in Scotland were "right to be outraged".

His comments came as his party welcomed a new poll which showed a majority of Scots backing Holyrood’s right to decide on holding an independence referendum.

The SNP Westminster leader said that Scotland had been "consistently sidelined" duting the Brexit process, and as a result should be allowed to hold indyref2.

The Survation poll, commissioned by Progress Scotland, found that 61 per cent of Scots backed the Scottish Parliament making the decision on whether or not an independence referendum should be held, compared to 39 per cent who thought Westminster should decide.

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The UK government has consistently ruled out granting the Scottish Government's demand for a Section 30 Order, to transfer the power from Westminster to Holyrood for the holding of a second independence referendum.

Boris Johnson has said that the 2014 vote was sold as a "once in a generation" event by the SNP, and Mr Blackford's party had to abide by the result, which saw 55 per cent of Scots voting to remain in the UK.

Ian Blackford has welcomed a new poll which shows the majority of Scots believe Holyrood should decide the timing of any second independence referendum.

However Nicola Sturgeon is expected to reveal her party's "next steps" in its determination to hold a second referendum in the Scottish Parliament this Wednesday.

Mr Blackford said the SNP would embark on "a broad-based campaign" to mobilise public opinion for indyref2.

"It is completely untenable and unsustainable for Boris Johnson and his Tory government to stand in the way of the democratic will of the people of Scotland.

“It’s now crystal clear that Scotland needs the full powers of independence so Scotland can take its place alongside other independent European nations, rather than being dictated to by a Tory government with no mandate to govern in Scotland."

He said the SNP would be working with civic Scotland and EU leaders in a bid to make sure a second independence referendum takes place this year. "We have to mobilise public opinion. I will be meeting with the EU ambassadors in London to press the case for Scotland's right to have that referendum and for our European friends to stand with us to keep that light on for us.

"We will be engaging with civic Scotland. I'm grateful that many figures in the Labour movement have agreed it is about Scotland's right to choose. Are the people of Scotland prepared to sit back and see a government in London that's going to ignore our democratic right?

"We will mount a broad-based campaign to make sure we can deliver on the mandate we have."

Mr Blackford also warned of the potential "economic and social damage" of Brexit.

He said: “As the UK prepares to leave the EU this week, Scotland must be given a choice over its own future. At a time when the Tories are ready to turn off the European light in the UK, an independent Scotland provides a beacon of hope to those who want to protect their rights as EU citizens - rights which are under threat if Scotland remains part of the UK.

“People in Scotland have consistently overwhelmingly rejected Brexit at the ballot box, and in winning 80 per cent of Scotland’s seats in 2019 General Election, the SNP has a cast-iron democratic mandate to give Scotland a choice."

Reacting to the Survation poll, his Westminster deputy Kirsty Blackman said: “Decisions about Scotland should be taken by the people who live there, not politicians in Westminster who have no mandate in Scotland.

“The Tories are completely out of step with people in Scotland - it’s clear that people in Scotland want Holyrood to decide on holding a referendum and it cannot be for Boris Johnson to continue to deny that mandate.

“There have already been welcome interventions from some senior Labour members who understand the need to respect Scottish democracy - it’s time the UK government woke up to reality and did the same."

The poll, which was commissioned by former SNP MP Angus Robertson's organisation, Progress Scotland found that - excluding "don't knows" which amounted to 12 per cent of those asked - 61 per cent believe the Scottish Parliament should ultimately decide on the holding of a future independence referendum while 39 per cent believe it should be Westminster.

The poll also found that if a pro-independence majority is elected to Holyrood at 2021 - excluding "don't knows" - 58 per cent believed that Holyrood should have the power to decide when a future referendum is held, compared to 42 per cent who did not.

Angus Robertson said: "There is a strong majority amongst voters in Scotland that it should be the Scottish Parliament that decides on the future holding of an independence referendum.

"Last week Boris Johnson declined the request from First Minister Nicola Sturgeon for Holyrood to have the powers over such a vote. Scottish public opinion appears to be on the side of the Scottish Government and Parliament which has voted in favour of such a move.

"Not only is there strong support from SNP and 'Yes' voters, but also from a significant minority of Labour and 'No' voters."

Ian Blackford: Independence is a 'beacon of hope' for people in Scotland