Boris Johnson's Scottish secretary has equated the SNP with extremist nationalists overseas in a dramatic escalation in unionist rhetoric.

Newly appointed Alister Jack claimed he could not distinguish mainstream independence supporters from xenophobic movements overseas.

Writing in the London Times, Mr Jack cited recent controversy over food packaging featuring the union flag as a sign of Scottish nationalists' "determination to find a grievance".

He said: "Scottish nationalists like to claim theirs is a different kind of nationalism, somehow uniquely benign.

"I am sorry but I am not sure I can spot the difference.

"Like nationalist movements the world over, it requires an enemy to make it thrive. It needs another to rail against. It's all about finding something at which to take offence, so they pick fights about flags on packaging, scour news bulletins for examples of imaginary bias."

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Mr Jack, a pro-Brexit businessman elected in 2017, was relatively low profile until Mr Johnson picked him for what is internationally often regarded as a nationalist Conservative administration.

Mr Jack's column made no criticism of 'othering' of foreigners or immigrants by Brexiteers or of ultra-UK patriotism.

His remarks came after First Minister Nicola Sturgeon once again distanced herself from the internet fringe of Scottish nationalism, saying there was no room for anti-English extremists in her party.

Ms Sturgeon and her justice secretary, Humza Yousaf have both in recent days expressed concern that their party's name leads to conflation with less savoury nationalist movements elsewhere.

Mr Jack's remarks also coincide with the suspension of a Conservative figure in Moray for making offence remarks about Ms Sturgeon losing a child during pregnancy.

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SNP MP Tommy Sheppard said: "This is utterly desperate stuff from Boris Johnson's man in Scotland.

"Sadly this is the kind of thing we've come to expect from the Tories."

After attacking nationalism, Mr Jack used his column in The Times to set out what he saw as an "historic oppirtunity" of Brexit - not least to get rid of the European Court of Justice. 

He wrote: "When the UK leaves the EU, Scotland will finally take back control of Scottish fishing waters, among the richest in the northern hemisphere.

"And once we are out of the EU, we will have a historic opportunity to introduce new farming funding schemes to support Scottish farmers - and we will make sure that they get a better deal.

"Post Brexit, Scottish people will not want to go back to living under the ECJ, they will not want to hand back control of fishing."

Some 62% of Scots rejected Brexit at the ballot box.

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Mr Jack added: "By strengthening the union, by showing the many advantages of belonging to the UK, we will also lift the second cloud of uncertainty facing Scotland, the First Minister's threat of a second independence referendum.

"That is a brighter vision than narrow, angry nationalism can offer. And it is why I am certain we can, and will, make a winning case for the union in the months and years ahead."

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The Scottish Secretary said yesterday's annual GERs figures showed "clearly how Scotland benefits from being part of a strong United Kingdom".

He wrote: "Yesterday [21 August] the Scottish Government published the annual 'Government Expenditure and Revenue Statistics', which show a nearly £13 billion black hole in the Scottish Government's finances.

"But being part of a strong UK means support for Scotland's economy. Despite contributing less in taxes, Scotland receives a bigger share of public spending. Scottish nationalism, however, chooses not to recognise that.

He added: "The Scottish Government spent much of last year railing against an imaginary 'power grab' - even though they were unable to name a single power that Holyrood would lose when we leave the EU.
"In fact, scores of new powers will lie with the Scottish Parliament after October 31.
"They claim that 'devolution is broken'. But that is just another fiction. Again, the reality is very different. It is the Nationalists who seek to break devolution so they can replace it with independence."