A LEADING member of a prominent hardline Scottish independence group says he is quitting the nationalist cause over the SNP’s new economic prospectus which he describes as "a betrayal".

Sean Clerkin of Scottish Resistance says he will no longer campaign for independence, in the wake of the long-awaited Sustainable Growth Commission report aimed at giving the economic argument for leaving the UK, with a series of recommendations on how Scotland could become a prosperous separate nation.

It aimed to show how an independent Scotland could match the growth levels of the some of the world's most successful small economies within a generation.

HeraldScotland: Sean Clerkin of The Scottish Resistance and Colin Lafferty at the Courtof Session in Edinburgh tuesday to support the Indy Camp case.Pic Gordon Terris/The Herald23/2/16 (57075540)

But Mr Clerkin, also a prominent anti-austerity protester says the document is "the longest suicide note for Scottish independence".

He is critical of proposals to continue to use the pound informally after independence, saying: "There is no Scottish currency, no Scottish central bank, we will not be economically independent. We will be relying on interest rates set by London. Our monetary policy will be set by London. We will not be independent."

READ MORE: Independence simply a 'piece of bureaucracy', says SNP deputy hopeful Julie Hepburn

The political agitator also strongly criticised plans to embark on a programme of deficit reduction which he feared would lead to "a lot of painful cuts to public services" and a move to a deeper austerity.

The campaigner, who is known for chasing former Scottish Labour leader Iain Gray into a sandwich shop in 2011 said: "I am walking away. I am withdrawing from the independence movement. That's what it means.

HeraldScotland:

"It is the most depressed I have ever felt politically in terms of campaigning for Scottish independence.

"I feel as though I have been betrayed. I feel as though the leadership of the SNP have betrayed myself and a lot of other people.

"Over the weekend I have had a long long think about it and basically, I am turning my back on independence and that is after a lifetime of commitment of going to meetings and marches. I have been in court on three occasions fighting for Scottish independence. "I have been arrested for breach of the peace to the point where I cannot get a job, and the bottom line is I have given everything for the cause and I feel absolutely betrayed about this.

"I have not come to this decision lightly. I have campaigned for Scottish independence all my life. This sustainable growth commission report is basically a neo-liberal wet dream for the right wing of the SNP.

"I am not a member of the SNP but I have always supported Scottish independence and the party has always presented itself until recently as a social democratic party, they get the basics right for working class people, to help tackle poverty, and improve the education and health service.

HeraldScotland:

"I have campaigned all my life for Scottish independence on the basis of social justice.

"But they have made this the blueprint for Scottish independence and it is not something that I can campaign on."

He spoke as the First Minister took to Twitter to defend the findings of the SNP's Growth Commission.

Nicola Sturgeon said the publication of the long-awaited report last week had provoked "lots of interesting comments", but added that some of them needed addressing.

READ MORE: Independence simply a 'piece of bureaucracy', says SNP deputy hopeful Julie Hepburn

She argued the commission "explicitly rejects austerity" and recommends above-inflation spending increases for the budgets of a prospective independent Scotland.

But Mr Clerkin, who also famously heckled Jim Murphy over "voting for austerity" said : "It will lead to a massive increase in austerity and lead to further poverty for working class communities that are already affected by the Westminister Tories.

"What it means is that billions of pounds of public sector cuts will have to take place and it means public services will be decimated from our health service through to social security through to local government. "And the bottom line is there is no incentive at all for working class people to vote for Scottish independence.

"If this is the kind of Scottish independent nation that we are going to have, I just cannot campaign for that. I will not campaign for that under any circumstances. As a socialist I cannot campaign on this agenda."

The First Minister wrote: "Reading lots of interesting comments about the Growth Commission - which is good.

"So much better to be discussing how to build a successful independent Scotland than just resigning ourselves to managing the decline of Brexit UK.

"A few points worth underlining though...

HeraldScotland:

"The report explicitly rejects austerity eg Part B p44 - 'Scotland should explicitly reject the austerity model pursued by the U.K. in recent years' and recommends above inflation spending growth each year.

"A marked contrast to the failed Westminster approach."

Ms Sturgeon added: "The report also stresses importance of investment to boost economy and that fiscal targets should not be at the expense of growth - another sharp contrast with Westminster.

"Indeed, it recommends fiscal stimulus both in the independence transition and in periods of low growth.

"The report's projections about deficit reduction are deliberately cautious.

"They make no assumptions about higher growth - and instead illustrate that even in worst case scenario independence is a better option that sticking with Westminster system that created the deficit but with the powers of independence and by following report's advice on how we can match the success of other small countries - particularly its recommendations on population - higher growth, more revenue and increased prosperity and fairness is the attainable prize."

READ MORE: Independence simply a 'piece of bureaucracy', says SNP deputy hopeful Julie Hepburn

She concluded: "So we have a choice - stay as we are, locked into the Brexit spiral and continued austerity that the Westminster parties offer no alternative to - or decide to equip ourselves with the powers to build our way to a better future.

"Lastly, policy choices in an independent Scotland will always be for the government of the day, so we should welcome debate - but without independence, these choices will always be far too limited."

Chaired by former SNP MSP Andrew Wilson, the Sustainable Growth Commission was announced by the First Minister in 2016.

Its report, Scotland: The New Case For Optimism, is the party's most significant contribution to the independence debate since the 2014 referendum.