THE SNP Government's preferred method for an independent Scotland to sign up fully to the European Union increases the risk of delay or even failure to its membership hopes, according to one of the UK's top experts on European law.

The view from Professor Kenneth Armstrong of Cambridge University, to be given to a Holyrood Committee this week, also highlights how Alex Salmond would have to rely on the UK Government to "pilot treaty revisions" as the existing member state and concludes that the planned move "seems ambitious, if not simply wishful thinking."

His view comes as, today, Alistair Carmichael declares in a speech in Brussels that the First Minister's intended Article 48 route a "dead-end" and urges the Scottish Government to "take its head out of the sand".

But in response, a spokesman for Nicola Sturgeon, the Deputy First Minister, branded his words hypocritical, given the Conservative's drive for an in/out referendum has threatened UK membership of the EU, and pointed to other academics' views, which "debunked" the No camp's scare story that an independent Scotland would be ejected. The SNP Government says Article 48 of the Treaty of the European Union is appropriate because Scots enjoy existing rights as members of the EU, while its opponents insist Article 49 is the correct route because if Scotland became independent, it would leave the current member state, the UK, and would have to apply for membership as a new member.

Prof Armstrongsaid: "Adopting the Article 48 TEU route rather than the Article 49 TEU route would deprive an independent Scotland of the autonomy to make the request to join the EU.

"Any opening of the treaty ­revision process would have to be negotiated and handled by the UK Government as a member state. It is precisely these arrangements that the White Paper derides and dismisses."

He notes that if the UK Government agreed to a Scottish request for treaty revision it would create a "very significant risk of issue-linkage" between the constitutional positions of Scotland and the UK in the EU.

"If that were to occur," suggests Prof Armstrong, "there is every reason to believe that, at best, the negotiating process at EU level would be lengthened, and at worst, the process could become intractable leading to failure."