There is no guarantee that people living in an independent Scotland will be able to keep their British citizenship, according to the UK Government.
The Scotland Office said the law stated that the grandchildren of British passport-holders living in a separate state would be forced to have Scottish citizenship.
The position appears to be at odds with the Scottish Government’s understanding, that the UK allows dual or multiple citizenship for British citizens.
Its white paper on independence states: “If a British citizen acquires citizenship and a passport of another country, this does not affect their British citizenship, right to hold a British passport or right to live in the UK.
“It will be for the rest of the UK to decide whether it allows dual UK-Scottish citizenship but we expect the normal rules to extend to Scottish citizens.”
The Scotland Office report said the SNP government was proposing a very wide model of citizenship that meant all British citizens living north of the border would be considered Scottish citizens, as would Scottish-born British citizens now living elsewhere.
It added that the government of the continuing UK would need to consider whether all British citizens living in Scotland could retain British citizenship upon independence.
The report said: “This cannot be guaranteed and could be dependent on any residency requirements or proof of affinity to the continuing UK. It is not possible to predict now what the decision of a future government of the continuing UK might be in this area.”
The report said current rules meant British citizens living outside the UK could not pass their British nationality on more than one generation. “The children of British citizens living in an independent Scottish state would be British citizens but their children and subsequent generations would not be,” it added.
But a spokesman for Scottish External Affairs Secretary Fiona Hyslop seized on a passage in the report that said it was “likely that it would be possible” for an individual to hold both British and Scottish citizenship.
“That is a welcome climb down from the hysterical scare stories Home Secretary Teresa May was promoting six months ago,” he said. “It follows the similar commonsense climbdown from the Treasury last week over the issue of debt.”