Nicola Sturgeon has warned Theresa May she will press ahead with plans for a second independence referendum with or without “constructive discussion” with the UK Government.
The first minister wrote to the prime minister yesterday requesting the power to hold another vote.
And she stressed it was not a question of if “but how” the Scottish Parliament’s mandate is respected.
This week MSPs backed the Scottish Government’s proposal to seek permission for a referendum by 69 to 59.
Unsurprisingly, the UK Government – which had already said it would not oblige – insisted last night it would not be entering into negotiations on the issue.
Mrs May has previously told the SNP leader, who wants to go to the people between autumn 2018 and spring 2019, that “now is not the time”.
The section 30 order letter, sent by email and courier to Downing Street, said there appeared to be “no rational reason” for the prime minister to stand in the way of Holyrood’s will.
“I hope you will not do so,” Ms Sturgeon wrote.
“However, in anticipation of your refusal to enter into discussions at this stage, it is important for me to be clear about my position.
“It is my firm view that the mandate of the Scottish Parliament must be respected and progressed. The question is not if, but how.
“I hope that will be by constructive discussion between our governments. However, if that is not yet possible, I will set out to the Scottish Parliament the steps I intend to take to ensure that progress is made towards a referendum.”
In a video message, the first minister added: “The prime minister has indicated she intends to ignore the will of the Scottish Parliament.
“If the Westminster Government continues to hold that line, it will go against the very foundations of devolution.
“So, I hope the prime minister changes her mind and acknowledges the people of Scotland are entitled to a choice at a time and in a way that is right for Scotland.”
About 62% of Scottish voters backed Remain in the EU referendum and the SNP’s manifesto for last year’s Holyrood elections said another ballot on independence should take place if there was a “material change in circumstances”, such as Scotland being removed from the EU against its wishes.
Number 10 confirmed the letter had been received by email and that a response would be sent in due course.
A UK Government spokeswoman said: “The prime minister has been clear that now is not the time for a second independence referendum and we will not be entering into negotiations on the Scottish Government’s proposal.
“At this point, all our focus should be on our negotiations with the European Union, making sure we get the right deal for the whole of the UK.
“It would be unfair to the people of Scotland to ask them to make a crucial decision without the necessary information about our future relationship with Europe or what an independent Scotland would look like.”