ASSURANCES that Brexit will not lead to a hard border in Ireland do not necessarily mean the same rule would apply to travel between an independent Scotland and England, leading academics have warned.

Nicola Sturgeon has repeatedly rejected suggestions that Scotland becoming independent to remain in the EU would mean passport checks when travelling south to a post-Brexit England, with the First Minister pointing out that the UK Government has already promised there would be no return of border posts between Northern Ireland and the Republic of Ireland.

However, at an event which saw some of the country's most respected constitutional and political experts gather to discuss the implications for Scotland from Brexit, The SNP leader's claim that the approach to Ireland could automatically apply to an independent Scotland was met with scepticism.

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Nicola McEwen, a University of Edinburgh professor and associate director of the Centre on Constitutional Change, said that troubled recent history of Ireland, as well as its geography, meant it may be viewed more sympathetically.

She said: "Clearly some of the issues that would come up in the context of an independence debate for Scotland, in terms of what you do with a land border between potentially an EU member state and the rest of the UK outside of the EU, will already have come up in the context of the island of Ireland.

"I think any of the concessions made there would certainly be part of the case the SNP would make for Scotland, [but] I'm not sure we could directly read over and that it would necessarily apply here too... There are different issues, more difficult issues, and perhaps less willing to make concessions given clearly Northern Ireland has a recent political difficulty, a recent political history, which is very difficult and nobody wants to reopen. The stakes are rather different in the case of Scotland, it seems to me."

Ms Sturgeon has said the UK Government "cannot get away" with warning of a hard border between England and Scotland post-independence, citing a speech in Belfast by the Conservative cabinet minister David Davis in which she said he assured people there that Brexit would not mean interrupted travel with the Republic of Ireland.

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However, Ms Sturgeon has been warned the English would be extremely concerned at the prospect of an independent Scotland becoming a "back door" for immigration from the EU, should she emerge victorious from a new referendum she has said she is "highly likely" to call. Academics have also said that restrictions may be placed on movement of goods and services between a Scotland in the EU and an England out of the bloc.

Professor David Heald, of the University of Glasgow, backed Professor McEwen's view, saying: "The political context is somewhat different. There's a degree of indulgence about Northern Ireland which enables people to treat it as a special case because of its recent history."

Earlier, Professor Michael Keating, a University of Aberdeen based academic and director of the Centre on Constitutional Change, abruptly dismissed the suggestion that the wishes of Scottish voters as expressed in the last two referendums - to stay in the UK and EU - could be respected with a bespoke post-Brexit deal.

Ms Sturgeon has previously floated a 'reverse Greenland' model, in reference to Denmark being in the EU while its territory is not, and her council of experts is examining unique options to protect Scotland's relationship with Europe.

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But Professor Keating said the Scottish Government voluntarily choosing to remain "in step" with Brussels post-Brexit in some policy areas would be "the best we could do".

He added: "We've heard a lot about reverse Greenlands, pick and choose, bespoke solutions for Scotland, none of which are really feasible. Greenland left the European Community in 1979, so they can be outside the EU even when Denmark is in.

"Leave aside they are small in population terms, the Greenland option for the UK would mean the UK staying in the European Union, and that little bit of it called England and Wales would come out. Scotland and Northern Ireland would somehow have to represent a state called the United Kingdom and take all of the decisions. It's just not going to happen."