Aileen McHarg, professor of public law and human rights at Durham University, has raised concerns over the proposals and recommends that powers should be given to MSPs, not the ministers.

Professor McHarg’s told Holyrood’s Finance and Constitution Committee that “we must question whether a ministerial power is the appropriate way to go at all”.

She said: “I don’t see in that case, there are any justifications really of pressure of time. I think it’s hard to see why those kind of policy choices should be seeded to the government rather than retained by the Parliament.

“My preference would be for primary legislation because ministerial powers of this nature ought to be seen as exceptional and as requiring special justification. It seems very hard to me to justify a power as extensive as this one in the hands of ministers.”

Part of the Scottish government’s EU Continuity Bill, which was the subject of the committee hearing, would hand Scottish ministers the power to continue to keep devolved law in line with EU law after the Brexit transition period ends this year.

The UK government’s white paper on the UK internal market is to act as a blueprint for trade after Brexit, and under these plans 111 powers will be transferred to Holyrood.

Professor McHarg said: “The internal market proposals, if they are implemented in the form that appears in the white paper, won’t technically prevent the use of the keeping pace power, but what they will do is probably render it less useful in practice because the effect of Scottish divergence will be overtaken by whatever happens in other parts of the UK.”

Professor Michael Keating, from Aberdeen University, told MSPs that the internal market plans are “really problematic” and offer a “risk of confusion”.

He said: “If we have rather ill-defined internal market provisions that allow the UK to intervene, prescribing mutual recognition that undermines Scottish regulation, if we have trade deals, if we have frameworks – it could create a great deal of uncertainty rather than more certainty for stakeholders.”