A legislative consent memorandum (LCM) lodged with Holyrood by Constitutional Relations Secretary Michael Russell says the bill undermines devolution and breaches international law.

Mr Russell said: “This is a defining moment that will determine both the future of the Scottish Parliament and whether or not the UK can be described as a partnership of equal nations.

“UK government ministers have accepted the bill will break international law. It would be equally outrageous if they decided also to break the constitutional convention that the Westminster Parliament does not legislate in devolved areas without the consent of the Scottish Parliament.

“The UK’s established constitutional rules mean that the consent of the Scottish Parliament is required for the UK Government’s Internal Market Bill to proceed. If the Parliament refuses to grant consent then that should kill the Bill stone dead. It will demonstrate beyond all doubt that the UK Government does not believe the UK to be a partnership of equals.

“This bill opens the door to a post-Brexit race to the bottom and will mean democratic decisions of the Scottish Parliament on public health, environmental standards, food standards and a range of other key areas can be over-ridden.

“The Scottish Government will ask the Parliament to make a decision on whether to grant consent next month and the memorandum we have published today sets out in detail why we could never recommend the Parliament agrees that its powers should be eroded so fundamentally.”