A second Scottish independence vote “will take place” despite Theresa May’s view that “now is not the time”, the SNP conference has been told.
The party’s deputy leader Angus Robertson said it would be “totally unacceptable” for Westminster to deny a referendum before Brexit is finalised.
Meanwhile, Mrs May has used a speech in Wales to defend “our precious Union”.
The PM indicated this week that her government would not approve the SNP’s preferred timetable for a referendum.
First Minister Nicola Sturgeon believed it was imperative for a vote on Scotland’s constitutional future to take place ahead of a deal being done on the UK exiting the European Union.
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At the earliest, that is expected in March 2019.
Ms Sturgeon has pinpointed the best time for a referendum would be between autumn 2018 and spring 2019.
In his speech to the conference in Aberdeen, Mr Robertson said: “Let there be no doubt – Scotland will have its referendum and the people of this country will have their choice. They will not be denied their say.”
He added: “Scotland’s referendum is going to happen and no UK prime minister should dare to stand in the way of Scotland’s democracy.”
However, Mrs May, who is to speak to the Welsh Conservative spring forum, will say she is working for “the whole country”.
She is launching her “plan for a brighter future”.
The SNP conference got under way just 24 hours after the Scottish and UK governments clashed over a second independence referendum.
Ms Sturgeon insisted that a referendum should go ahead on her timescale.
‘Bad for us all’
A key theme of the prime minister’s speech to the Welsh Conservative forum meeting in Cardiff was a defence of the UK.
She said the “precious bond” between England, Scotland, Wales and Northern Ireland was much more that just “constitutional artefact”.
Mrs May went on to say that a second Scottish independence referendum would be “bad for Scotland, bad for the United Kingdom, and bad for us all”.
The prime minister added: “The coming negotiations with the EU will be vital for everyone in the United Kingdom.
“Every person, every family, every business, every community the length and breadth of the United Kingdom – England, Scotland, Wales and Northern Ireland.
“As the prime minister of this United Kingdom, I will always ensure the voices and interests of England, Scotland, Wales and Northern Ireland are represented as we negotiate to leave the EU.”
Mrs May had already accused the SNP of forcing a “fundamentally unfair” independence referendum that would damage Brexit negotiations.
Writing in the Times, she said: “The SNP is trying to force the UK government to agree to something that is fundamentally unfair to the Scottish people.
“It wants to ask them to make a crucial decision without the necessary information.
“They would not know what the new partnership with the EU would look like, or what the alternative of an independent Scotland would be. It would simply not be fair.”
The article follows a television interview on Thursday, in which she said “all our energies” should be focused on negotiations with the European Union.
At the SNP conference later, Deputy First Minister John Swinney will address domestic Scottish matters as the parties in Scotland prepare for May’s local government elections.
Mr Swinney said the spring conference, which will be attended by 2,500 delegates, would “underline our party’s top priorities of education, the economy and our public services”.
Speaking to the BBC’s Today programme, he said the Scottish Parliament would discuss the request to hold another Scottish independence referendum next week and he was confident a vote to ask for one would be passed.
Mr Swinney said it would then be up to Mrs May to “recognise the democratic wishes of the people of Scotland”.
He told presenter John Humphrys: “The PM has the capacity to change her mind. Theresa May has demonstrated big style this week that she has to change her mind in the face of political reality. Theresa May would be ill-advised to stand in the way.”
SNP deputy leader Angus Robertson says Scotland ‘will have its referendum’}