The UK Government is stepping up its campaign against Scottish independence by questioning the legal status of a separate Scotland.
It insists that while the remainder of the UK would inherit more than 14,000 international treaties, an independent Scotland would not.
In what it calls an "unusual step", Whitehall has published its legal advice on the international law aspects of Scottish independence.
It claims that international precedent dictates that an independent Scotland would become a "new state" and what is left of the UK would be considered a "continuing state".
According to its legal opinion, only the remainder of the UK would automatically continue to exercise the same rights, obligations and powers under international law as the UK currently does, and would not have to renegotiate existing treaties or re-apply for membership of international organisations.
Currently, the UK is signed up to several thousand treaties and has membership of international organisations such as the United Nations, European Union, Nato, the International Monetary Fund and the World Trade Organisation.
The UK Government's legal opinion was written by Professor Alan Boyle, of Edinburgh University, and Professor James Crawford, of Cambridge University.
Alistair Darling MP, the former chancellor and leader of the pro-Union 'Better Together' campaign, told Sky News: "This is a formidable legal opinion from two internationally respected lawyers. Their opinions have to be taken very seriously and they just can’t just be dismissed by the nationalists.
"Again, it begs the question where is the advantage to Scotland of breaking its links with the rest of the UK, losing influence as well as all the other economic advantages that come from being together?
"It's high time the nationalists told us the basis of their increasingly discredited claims."
Scottish Secretary Michael Moore will launch what Downing Street describes as a series of 'Scotland Analysis Papers' in a speech in Edinburgh.
The event has drawn criticism from the SNP-controlled Scottish Government.
Scotland's Deputy First Minister Nicola Sturgeon told Sky News: "This is an act of breathtaking arrogance by this Tory-led UK Government, which completely shatters their claim that Scotland is an equal partner within the existing UK - it will only serve to boost support for an independent Scotland.
"The fact of the matter is that this is an opinion - no more, no less. Other constitutional and legal experts take a completely different view.
"For example, Professor David Scheffer, constitutional law expert and former US ambassador, said only recently that 'the break-up would be viewed as two successor states of equal legitimacy - not size, wealth or power, but legitimacy' ...this means a continuation for both states."
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