A fresh row has broken out between SNP ministers and the UK Government over the future of devolution after the Tories announced plans for a "Brexit Freedom Bill".
Downing Street is weighing up plans which would hand Boris Johnson the ability to remove regulations previously set by the European Union.
John Swinney today claimed the Scottish Government was only informed of the move on Saturday during a brief phone call with Attorney General Suella Braverman.
The Deputy First Minister accused the Tories of "no prior consultation, no engagement, no dialogue" on the issue.
The row centres on how the EU imposes set rules for member states on a variety of issues including environmental protections, food and drink standards and consumer issues.
But following Brexit there have been clashes between the Scottish Government and Westminster over who should now take responsibility for regulations previously set by Brussels.
SNP ministers have repeatedly warned that senior Tories view Brexit as an opportunity to claw back powers from the Scottish Parliament.
A controversial Internal Market Bill was passed by MPs last year despite opposition from the devolved governments in Edinburgh, Cardiff and Belfast.
Downing Street now claims current rules mean it could take several years to scrap EU laws and the process should be sped up.
Swinney said: "On Saturday morning, the constitution secretary Angus Robertson took part in a call with the Attorney General in which what was reported this morning was announced to us.
"No prior consultation, no engagement, no dialogue, no enhancement of the way the administrations work together.
He added: "I think it would be good if the UK Government was to have actually engaged about what was the right way to proceed with this, as opposed to summoning a minister for a brief call on a Saturday morning.
"The danger is the powers of the Scottish Government and Welsh Assembly could be undermined as a consequence.
"If you want evidence of about the undermining of the Scottish Parliament, have a look at the Internal Market Bill, which is already on the statute book, designed by the UK Government to use the excuse of Brexit to undermine the powers of the Scottish Parliament.
"That's the reality of the threat we face to devolution. It is a threat I have been very open about in statements I have made to the public.
"The Scottish Parliament's powers are under real threat - and that threat comes from the UK Government."
Boris Johnson insisted a "Brexit Freedoms Bill" will make it easier to change thousands of EU-era regulations that remain in force.
He said the it would allow the UK to set growth-friendly rules for "cutting edge technologies of the future".
In an announcement for the two-year anniversary of Brexit, No 10 said its new bill would ensure changes can be made more easily.
Johnson said it would allow the UK to shape better regulations in areas where it is "strong" - citing areas like cyber technology, artificial intelligence, and gene editing.
"There are things that we can do differently in a way that will encourage business to invest even more," he said.
"We won't diverge for the sake of it, but we're going to make sure this is the number one place to invest and do business because of freedoms that we have."
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