In his speech at the virtual Scottish Conservative conference on Sunday, the secretary of state for Scotland claimed it was the nationalist party that was “imperilling the very foundations of the devolution settlement”.
Mr Jack also claimed Nicola Sturgeon was “rattled” by the way the SNP had been held to account by the Scottish Conservatives in Holyrood.
In the latest effort by the UK Government to bolster support for the union, the speech also highlighted the Covid-19 vaccine rollout as evidence of the strength of the Union, alongside the financial response by the UK Government to the pandemic.
Mr Jack said: “Had we followed the SNP’s advice on vaccines and waited for the flat-footed EU, we would still be in the vice-like grip of the pandemic instead of confidently looking forward to better days.
“There can be no more eloquent expression of the success of the Union than this brilliant UK-wide approach.”
On a second Scottish independence referendum, Mr Jack said it was “chilling” the SNP were planning indyref2 during a pandemic, labelling Westminster leader of the party, Ian Blackford, a “champagne separatist”.
He said: “It is chilling that with the monumental task of recuperating from a pandemic still ahead, supposedly serious politicians can spend even a moment contemplating the reckless folly of another referendum.
“The SNP have been counting votes not yet cast for months now, boasting about how the election will give them a mandate for whatever they want, with no heed for what the people of Scotland want.
“One thing is clear – both votes for the Conservatives is the way to be sure of stopping the separatist SNP breaking up Britain.”
Praising the work of Scottish Tories leader Douglas Ross, the secretary of state said the SNP had been “taking the public for fools” and were “distracted by internal bickering”.
Mr Jack said: “Time and again they have told fairy stories while playing fast and loose with the rules, imperilling the very foundations of the devolution settlement.
“I am delighted that the Scottish Conservatives have, under the leadership of Douglas Ross, done so much to expose this SNP duplicity.
“On his watch, the SNP have had secrets they wanted to bury dragged into the cleansing sunlight of scrutiny.
“They have been forced to think again on wrong-headed legislation, been held to account for their sophistry.
“They believed their own publicity and thought they could walk on water. Well, Douglas and our Holyrood team have dumped them in the briny … Nicola Sturgeon is rattled.”
On the levelling-up fund, described by Scottish Government minister Ivan McKee on Saturday as a “raid on devolved spending”, Mr Jack said it would put money “local communities crave directly into their hands”.
He said: “Together, we intend to ensure this money is spent for the betterment of people the length and breadth of Scotland, and not left to moulder in the coffers of Bute House.
“Here, then, is true devolution with central government putting the power and the money local communities crave directly into their hands.”