Boris Johnson has formally rejected a call from the Scottish First Minister for Holyrood to be given the power to hold a second independence vote.

In a letter to Nicola Sturgeon, the under-fire Prime Minister said he had “carefully considered” her request – but he insisted that he could “not agree that now is the time to return to a question which was clearly answered by the people of Scotland in 2014”.

Ms Sturgeon said the refusal to grant the Scottish Parliament the power to hold a vote could be one of Mr Johnson’s last acts as Prime Minister.

The letter, which the Scottish First Minister revealed on Twitter, came in the wake of a series of resignations from government at Westminster, with many Tories now urging the PM to quit.

Ms Sturgeon insisted: “To be clear, Scotland will have the opportunity to choose independence – I hope in a referendum on 19 October 2023 but if not, through a general election.”

But Mr Johnson told her: “I have carefully considered the arguments you set out for a transfer of power from the UK Parliament to the Scottish Parliament to hold another referendum on independence.

“As our country faces unprecedented challenges at home and abroad, I cannot agree that now is the time to return to a question, which was clearly answered by the people of Scotland in 2014.”

Mr Johnson continued: “Our shared priorities must be to respond effectively to the global cost-of-living challenge, to support our NHS and public services as they recover from the huge disruption of the Covid-19 pandemic, and to play our leading part in the international response to Russian aggression in Ukraine.

“These are common challenges across the United Kingdom, which deserve our full attention.”

The letter comes just over a week after the SNP leader formally unveiled plans to hold a second vote on Scottish independence on October 19 2023.

As well as asking for the power to hold such a vote to be transferred to Holyrood, UK Supreme Court judges have also been asked if the Scottish Government can hold a consultative ballot on the issue.

Ms Sturgeon has also made plain that if both Westminster and the courts rebuff her attempts to hold another referendum the SNP will use the next UK general election as a ‘de facto referendum’ on Scottish independence.

Labour meanwhile argued that Scots were being let down by governments on both sides of the border, with constitution spokesperson Sarah Boyack stating: “The people of Scotland are being failed by an SNP government at Holyrood that is obsessed with separation and an imploding and corrupt Tory government at Westminster.

“Boris Johnson and Nicola Sturgeon are two sides of the same coin.

“Neither the Tories nor the SNP are focused on tackling the cost of living crisis or rebuilding our services from the pandemic, and both are damaging the future of devolution.”

Scottish Greens MSP Gillian Mackay said the letter came as “yet another slap in the face to the people of Scotland, who have repeatedly sent pro-independence majorities to Holyrood and Westminster”.

“The people will not continue to be held hostage by the most unpopular Prime Minister in history,” she said.

“We will ensure that Scotland’s future is placed firmly in the hands of the people who live here.”