Jobs in Scotland would be put under “serious risk” without new legislation on post-Brexit trading rules, the Scottish Secretary has insisted.

While Scottish Government ministers have branded the controversial UK Internal Market Bill a Westminster “power grab”, their UK Government counterparts insist the legislation will see more powers transferred to all the devolved governments.

From January 1, when the UK’s transition period comes to an end, powers will be returned from Brussels to the administrations in Scotland, Wales and Northern Ireland, they stated.

Scottish Secretary Alister Jack said the new legislation was about “respecting and strengthening devolution” by ensuring trading between the four nations can continue as it currently does.

Holyrood Constitution Secretary Mike Russell has, however, vowed the Scottish Government will not consent to the Bill.

He insisted that Scottish ministers “couldn’t recommend consent to a Bill that undermines devolution and the Scottish Parliament, and which, by the UK Government’s own admission, is going to break international law”.

Mr Russell said: “This is a shabby blueprint that will open the door to bad trade deals and unleashes an assault on devolution the like we have not experienced since the Scottish Parliament was established.

“We cannot, and will not, allow that to happen.

“It will open the door to a race to the bottom on food standards, environmental standards and will endanger key public health policies such as minimum unit pricing.

“It will also deliver a hammer blow to the Scottish economy by making it harder for the UK Government to conclude free trade agreements if other countries think the UK won’t meet its obligations.”

UK Business Secretary Alok Sharma said the legislation would protect the UK’s “highly integrated market” by “guaranteeing that companies can continue to trade unhindered in every part of the UK after the transition period ends and EU law falls away”.

He added: “Without these necessary reforms, the way we trade goods and services between the home nations could be seriously impacted, harming the way we do business within our own borders.

“Now is not the time to create uncertainty for business with new barriers and additional costs that would trash our chances of an economic recovery.”

Our Scottish brand is known throughout the UK and it is vitally important to us that we can continue to trade freely in all parts of the country

Mr Jack said: “Without this legislation there would be a serious risk to our jobs and businesses which is not surprising given the rest of the UK is Scotland’s biggest market, worth £55 billion a year, and a massive 60% of all our exports.”

Some business leaders in Scotland welcomed the new Bill, with Audrey Baxter, chief executive of Baxters Food Group Limited, stating: “Our Scottish brand is known throughout the UK and it is vitally important to us that we can continue to trade freely in all parts of the country.

“We welcome the UK Government’s internal market legislation which will preserve and protect the current trading conditions. This will continue to guarantee a level playing field for companies like ours and is crucial to our continued success.”

David Lonsdale, director of the Scottish Retail Consortium, said: “Scottish consumers and our economy as a whole benefit enormously from the UK’s largely unfettered internal single market, as economies of scale and regulatory consistency helps reduce business costs which in turn keeps down shop prices and provides greater consumer choice.

“We welcome the government’s recognition of that and the aim to keep it as simple and as easy as possible for retailers and other firms to continue to trade.”