The Prime Minister made the controversial comments in a Zoom call with MPs for northern England.
Scottish First Minister Nicola Sturgeon immediately seized on the comments to make the case for independence.
Sources close to Mr Johnson last night tried to limit the damage by insisting that he was referring to the fact devolution has been ‘used by separatists and nationalists to break up the UK’, but Downing Street did not deny the comments.
It comes amid rising tensions within the United Kingdom as support for Scottish independence dramatically surged in recent weeks with almost six in 10 Scots now supporting the break up of the United Kingdom.
And SNP Westminster leader Ian Blackford said a second vote on splitting the country ‘must’ happen in 2021 – insisting it had already been delayed from this year.
He insisted that Miss Sturgeon will have grounds to hold a referendum ‘quickly’ if the SNP wins Holyrood elections in May.
Devolution has been a ‘disaster’ and was the biggest mistake made by Tony Blair when he was PM, Boris Johnson told colleagues
Scottish First Minister Nicola Sturgeon immediately seized on the comments to make the case for independence
It comes amid rising tensions within the United Kingdom as support for Scottish independence dramatically surged in recent weeks with almost six in 10 Scots now supporting the break up of the United Kingdom
Support for Scottish independence soars to record high in new poll as 58 per cent now back move to split up the UK
Support for Scottish independence has dramatically surged in recent weeks with almost six in 10 Scots now supporting the break up of the United Kingdom.
The analysis by Ipsos Mori for STV found that among those who would be likely to vote in an independence referendum, 58 per cent say they would vote Yes, while 42 per cent would vote No.
At the last referendum in 2014, 55 per cent of Scots voted to stay a part of the UK, with 45 per cent backing secession.
Additionally, almost two thirds (64 per cent) of Scots believe that Mr Johnson should permit a fresh vote within the next five years if the SNP wins a majority in Holyrood elections next May. This is something he has ruled out.
But Downing Street ruled out backing a new referendum today with the Prime Minister’s official spokesman saying: ‘In 2014 the Scottish people voted to keep the UK together. Both sides committed to respecting that decision and the First Minister promised it would be a once-in-a-generation vote.’
Mr Johnson’s remarks came in a call with 60 MPs which he made in self-isolation.
He said: ‘Devolution has been a disaster north of the border.’
He added that it was former prime minister Mr Blair’s ‘biggest mistake’ when it was introduced in the late 1990s.
The Labour government introduced devolution for Scotland, including the parliament in Edinburgh, in 1999.
Scottish Tory leader Douglas Ross last night insisted devolution has not been a disaster, but the SNP’s obsession with independence has been.
Mr Johnson also told MPs that he did not currently ‘see a case’ for handing down more powers from Westminster to Scotland, Wales and Northern Ireland.
However, a No10 source said: ‘The PM has always supported devolution, but Tony Blair failed to foresee the rise of separatists in Scotland.
‘And leaving the EU means we must strengthen and protect the UK economy with the UK Internal Market Bill. Devolution is great – but not when it’s used by separatists and nationalists to break up the UK.’
Mr Johnson’s intervention comes days before the Scottish Conservative conference is due to get under way.
Mr Ross said: ‘Devolution has not been a disaster. The SNP’s non-stop obsession with another [independence] referendum – above jobs, schools and everything else – has been a disaster.’
Miss Sturgeon said on social media: ‘Worth bookmarking these PM comments for the next time Tories say they’re not a threat to the powers of the Scottish Parliament or, even more incredibly, that they support devolving more powers.
‘The only way to protect and strengthen the Scottish Parliament is with independence.’
Mr Ross is due to use the Scottish Tory virtual conference, which begins on Friday, as the launchpad for next year’s Scottish Parliament elections following bleak recent polling for the party.
Earlier this month, he said the Prime Minister may be the reason support for independence has soared in recent polls.
The Prime Minister made the controversial comments in a Zoom call with MPs for northern England. Pictured: Mr Johnson after he was instructed to self-isolate by NHS Test and Trace
Boris Johnson said devolution was former Labour prime minister Tony Blair’s ‘biggest mistake’ when it was introduced in the late 1990s’
Labour’s Shadow Scottish Secretary Ian Murray said: ‘This confirms that Boris Johnson doesn’t believe in devolution and would put the future of the United Kingdom at risk’
Labour’s Shadow Scottish Secretary Ian Murray said: ‘This confirms that Boris Johnson doesn’t believe in devolution and would put the future of the United Kingdom at risk.’
He added: ‘Devolution is one of Labour’s proudest achievements and we will always fight for a strong Scotland in the UK. Scotland deserves better than two governments obsessed by division – Labour will work to bring our country together.’
Mr Johnson has ruled out a second referendum on Scottish independence following the 2014 vote, in which breaking away from the UK was backed by just 44.7 per cent of Scots.
Miss Sturgeon has called for another referendum if the SNP win the elections next May.