THE European Union’s absence from the SNP’s long-awaited independence blueprint has been compared to the ghost at the feast that haunts Shakespeare’s guilt-ridden Macbeth.

Dr Kirsty Hughes, director of the Scottish Centre on European Relations think tank, said the EU was “like Banquo’s ghost” in the Growth Commission report, with its invisible presence felt throughout but never fully addressed.

The 354-page SNP document, which was published last week, recommends an independent Scotland keep the pound for at least 10 years while limiting public spending in an attempt to reduce the deficit.

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But experts insist this would effectively postpone Scotland’s membership of the EU, as it could not join up without its own monetary policy.

In a blog post, Ms Hughes said: “Like Banquo’s ghost, the EU makes rather few appearances in the report of the SNP’s Growth Commission. But its rather invisible presence can be felt throughout.”

It comes as splits continued to emerge over the blueprint, with a former deputy party leader saying it made him despair and a former MP describing it as “conservative”.

Former deputy Jim Fairlie and former MP George Kerevan both attacked the report, focusing on its plan to keep using the pound informally, rather than creating a Scottish currency.

Mr Fairlie said the policy meant a second referendum would be lost before it started, while Mr Kerevan said it let down the SNP’s working-class base.

Keeping the pound would leave Scotland unable to set its own monetary policy, with interest rates determined by the Bank of England.

Ms Hughes said this would be a “clear block in the way of an independent Scotland’s accession to the EU”, and argued Scotland’s future relationship with Europe was simply not addressed in the report.

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She raised the prospect of a hard border between Scotland and England if one was in the customs union and the other wasn’t, while also questioning whether plans to attract high-skilled, high-earning migrants would fall foul of EU state aid rules.

Meanwhile, former MEP Andrew Duff – a visiting fellow at the European Policy Centre and president of the Spinelli Group, which pushes for a federal Europe – argued that if Scotland did apply for EU membership while using sterling, it could be forced to negotiate its entry via the Bank of England and the UK Treasury.

He said this would lead to Whitehall being a “third party” to any negotiations between an independent Scotland and the EU, adding: “They would have to be at the table.”

First Minister Nicola Sturgeon was asked about the report’s currency plan at an event in Brussels on Monday.

She said sterlingisation, rather than a formal currency union of the type the SNP proposed in 2014, would not be the same as Panama using the US dollar, because Scotland already used the pound.

She said: “The report is a set of recommendations. The SNP has to consider them and deliberate and come to a view.”

Ms Sturgeon said Scotland would not currently meet the criteria for joining the euro, a long-term option only briefly referred to in the Commission report.

She added: “It’s not my party’s position to have Scotland go into the euro, and I don’t envisage that changing.”

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Scottish Liberal Democrat leader Willie Rennie suggested Ms Sturgeon was already distancing herself from the report’s recommendations.

He said: "This could be the biggest climb-down since the Grand Old Duke of York.

"The Growth Commission was supposed to be a game changer and the SNP’s best shot at convincing the majority of people they had learned the lessons of the last independence referendum.

"Yet it’s taken all of three days for the First Minister to brush it off. All this report has really done is divide the nationalist movement."