The UK government is expected to argue that the test for whether legislation is within Holyrood’s competence requires it to be first passed. Nevertheless the UK government believes such legislation would be ultra vires of the Scottish Parliament’s powers as set out in the Scotland Act.

A UK government spokesperson said: “We have been clear that now is not the time to be discussing another independence referendum, when people across Scotland want both their governments to be working together on the issues that matter to them and their families.

“However, following the Lord Advocate’s referral of the Scottish government’s draft Scottish Independence Referendum Bill, the UK government has … lodged its initial response with the Supreme Court.

“The papers confirm that the Advocate General for Scotland will become a formal party to the case, and ask the court to consider whether it should accept the Lord Advocate’s referral.”

A spokesperson for First Minister Nicola Sturgeon said in response: “People in Scotland have voted for a Parliament with a clear majority in favour of independence and with a mandate for an independence referendum. The Scottish government fully intends to offer the Scottish people the choice of independence and has set out how it will do so.

“The UK government’s repeated attempts to block democracy – which now seem to extend to an unwillingness to even make a substantive argument before the Supreme Court – serve only to demonstrate how little confidence it has in its case for the union.

“However, whether the reference is accepted, how long it takes to determine and what judgment is arrived at are all matters for the Court to determine. The reference is now before the Supreme Court, and the Court should be allowed to fulfil its function.”