During a visit to a vaccination site in north London, the prime minister was asked if he would legally challenge first minister Nicola Sturgeon’s plans for an advisory independence referendum if the SNP wins a majority in May’s Holyrood elections.
Johnson said: “The whole UK is going through a pandemic, I think what the people of the UK want to see is everybody focusing on beating that pandemic, which we are, rolling out the vaccine, and getting ready to bounce back from that pandemic and have the strongest possible economic recovery.
“I think people also can see everywhere in the UK the visible benefits of our wonderful union.
“A vaccine programme that is being rolled out by a National Health Service, a vaccine that was developed in labs in Oxford and is being administered by the British Army, so I think the strengths and advantages of the union speak for themselves.”
The SNP wants a “legal referendum” to be held after the pandemic if there is a pro-independence majority following the parliamentary elections in May.
The party has revealed a "roadmap to a referendum", setting out an 11-point plan on how it intends to take its plans for a second vote forward.
It says any attempt by the UK government to challenge the legality of the referendum will be “vigorously opposed”.
Johnson has repeatedly stated his opposition to a second independence referendum.
Watch: Nicola Sturgeon extends lockdown measures until mid-February
Speaking to the BBC’s Andrew Marr on Sunday, the prime minister said referendums “don't have a notably unifying force in the national mood” and “should be only once in a generation”.
Asked about his comments later on in the show, Sturgeon said: “He's frightened of democracy. The polls now show a majority of people in Scotland want independence.
“If the SNP win the Scottish election in a few months' time on a proposition of giving people that choice, then what democrat could rightly stand in the way of that?
“Boris Johnson clearly just fears the verdict and the will of the Scottish people.”
She also said there was no reason to delay the elections because of the pandemic, given that many countries have had elections over the last year.
The 2014 independence referendum resulted in a 55.3% vote against Scottish independence.
A Sunday Times poll found that Scotland would vote for independence by a margin of 52% to 48% who wouldn’t, excluding those who “didn’t know”.
It also found that 51% of voters in Northern Ireland want a border poll in the next five years.
Watch: UK 'risks becoming a failed state' says former prime minister
Former prime minister Gordon Brown said Britain risks becoming a “failed state” and that COVID has exposed "tensions" between Whitehall and the nations and regions.
Writing in the Sunday Telegraph, Brown, a Scot, said “the choice is now between a reformed state and a failed state.
“It is indeed Scotland where dissatisfaction is so deep that it threatens the end of the United Kingdom.
“For the first time, a majority of Scots now feel, according to recent polls, that Scotland and the rest of the UK are moving inexorably in opposite directions and nearly half of all Scots who have a view believe – against all the evidence – that Scotland would be better off economically independent, and they feel that the Union undermines Scotland's distinctive identity.
“While the crisis is deepest in Scotland, it is far from alone.”
Scottish Labour interim leader Jackie Baillie accused the SNP of prioritising the push for independence over the coronavirus response.
He said: “Scotland is deep in turmoil with thousands facing a cost of living crisis and thousands more people being lost to the virus.
“It is inexcusable that at this time of acute crisis the SNP seeks to put its plan for independence above everything else.”
Scotland’s relationship with the EU is now governed by trading and travel agreements made by the UK government on Christmas Eve after the Brexit transition period formally ended on 31 December.
The first minister tweeted asking for the EU to “keep a light on”, saying Scotland will be “back soon”.
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