A FORMER US Ambassador has accused Westminster of trying to have it both ways for arguing that an independent Scotland would have to carry its share of UK liabilities such as debt, without inheriting any of the international treaty and membership rights.

Professor David Scheffer of the Centre for International Human Rights in Chicago has written a legal opinion arguing the UK's claim to be the "continuing state" in the event of independence, but that Scotland have to bear its share of UK liabilities, rests "on very thin ice".

His paper, published on Deputy First Minister Nicola Sturgeon's Scottish Referendum blog, said: "The Whitehall report is at its weakest when examining the rights of EU citizens in Scotland (Scots are also EU citizens), and even at times with respect to EU membership per se."

Professor Scheffer disputes the UK Government's claims that Scotland was "extinguished as a matter of international law" 300 years ago, describing this as built on a "pyramid of presumption".

He said: "Some would strongly disagree with this conclusion and argue the Scottish people retained their right of self-determination within a distinct part of Great Britain that continued with an autonomous national character."

Using the legal term for a legal status drawn from specific circumstances, he added: "The sui generis character of Scotland derives from its past sovereignty reasserting itself in a modern application of self-determination culminating in the 2014 referendum."

Ms Sturgeon said: "Professor Scheffer's expert opinion makes crystal clear that the UK Government's claims about Scotland are nothing more than assertions. Scots are EU citizens, Scotland has maintained a unique legal character, and the idea that Scotland could be deprived of all the rights we have acquired while being expected to take on the liabilities built up by Westminster is contradictory. "

The Better Together campaign has highlighted the problems independence could cause for Scots who currently receive specialist treatment in England. Labour's Jackie Baillie, a director of Better Together, said: "The NHS has been built by the people of the United Kingdom to look after the people of the UK. If we leave the UK, it is obvious that all of this will change. We would be replacing a simple, internal relationship with an international, cross border one."

The Scottish Government said: "Scotland's NHS is already run by the Scottish Government, in the best interests of the people of Scotland."