The SNP will call on the UK Government to rule out a “Brexit power grab on Scotland” as MPs debate the party’s motion calling for an extension to the transition period.

Ian Blackford, SNP Westminster leader, said Tory plans represent the “biggest threat to devolution” since the Scottish Parliament was reconvened in 1999.

In the debate on Wednesday, he will also call on Prime Minister Boris Johnson to accept the extension to the transition period on offer from the EU, warning crashing out would be damaging at any time and “extremely reckless” in the middle of a global pandemic.

Scottish Government analysis has found ending the transition period in 2020 could remove £3 billion from the Scottish economy in just two years – on top of the impact of coronavirus.

Speaking ahead of the Commons debate, Mr Blackford said: “Tory plans for a Brexit power grab on Scotland represent the biggest threat to devolution since the Scottish Parliament was reconvened in 1999.

“The threat to our NHS, agriculture, environment and economy is growing by the day as Boris Johnson tramples over Scotland’s interests to satisfy Donald Trump’s trade deal demands.

“The Tory government must rule out any attempt to roll back devolution, which the SNP will resist every step of the way, and put the economy first by extending the Brexit transition period.”

Mr Blackford said that with just six months left until the transition period ends, little progress has been made and there is no good deal in sight.

An extension would have bound us into future EU legislation, without us having any say in designing it to make sure it suits the interests of people in Scotland and Wales

He said that all of the options being considered would inflict lasting damage on the economy and leave the UK “poorer and worse off”.

Mr Blackford added: “With businesses struggling to survive and thousands of jobs being cut, we cannot afford a Tory Brexit crisis piled on top of the coronavirus emergency we already face.

“Crashing out of the EU would be damaging at any time but it is extremely reckless in the middle of a global pandemic.

“Scotland has been completely ignored throughout the Brexit process and we have been shut out of the trade talks.

“It is clearer than ever that the only way to properly protect Scotland’s economy and our place at the heart of Europe is to become an independent country.”

A UK Government spokesman said: “The transition period ends on 31 December 2020, which is enshrined in law. This was recognised by all parties at the High Level Meeting on 15 June.

“The UK Government was elected on a clear manifesto commitment that the transition period would end this year. Extending the transition period would only exacerbate uncertainty for businesses and citizens in Scotland, Wales and across the UK.

“An extension would have bound us into future EU legislation, without us having any say in designing it to make sure it suits the interests of people in Scotland and Wales.

“We would still have to make large-scale payments to the EU and would still be constrained by state aid rules meaning we need EU approval for support measures to Scottish and Welsh industries.

“And overall we would be bound to follow the EU’s decisions, which reasonably enough will be made in the interest of the 27 not the 28.

“Brexit is about economic independence and we gain more by being able to design our own rules to suit the best interests of our businesses and people in future.”