The SNP is calling on the prime minister to outline how Scotland can hold another independence referendum.
The party’s new deputy Westminster leader, Mhairi Black, has written to Rishi Sunak to say he must “show leadership” on the issue.
Ms Black – who took on her role earlier this week – pointed to her SNP colleague Philippa Whitford, who asked about the options during Prime Minister’s Questions.
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Mr Sunak had responded by saying he “fully respected” the decision of the Supreme Court, which ruled last month that UK government consent was needed to call another vote.
But Ms Black also pointed to the words of cabinet ministers Alister Jack and Michael Gove, who have previously granted there could be another referendum if there was support for it in Scotland.
She wrote: “This time, instead of helplessly hiding behind the Supreme Court, the prime minister could actually show leadership and outline exactly how Scotland can choose to exercise its democratic right in this so-called ‘voluntary union’.
“However, the prime minister must be in no doubt that for every day Scotland’s democracy is denied, the stronger our case will grow.”
SNP leader and Scotland’s First Minister Nicola Sturgeon has said her party will use the next election as an informal referendum.
But her critics have warned this would have no legal validity, urging the SNP to “set aside divisive constitutional issues”.
A spokeswoman for the UK government said the people of Scotland want their leaders “to be concentrating on the issues that matter most to them – like growing our economy, getting people the help they need with their energy bills and supporting our NHS”.
They added: “As the prime minister has been clear, we will continue to work constructively with the Scottish government to tackle our shared challenges.”
Scotland held an independence referendum in 2014 and just over 55% voted to remain part of the UK.
But the pro-independence SNP, which has led the country since 2007, believes it has a mandate to hold a fresh vote because of its continued success in elections – the majority of members in the Scottish Parliament back independence – and because of the change in circumstances since Brexit.
A poll by Ipsos Scotland released this week showed 56% of decided voters supported independence, while 53% of people said they would vote for the SNP in the next general election if it were to be used as a de facto referendum.