WESTMINSTER and Holyrood are at loggerheads over a key aspect of the devolution deal – and urgent action is needed, MSPs say.

In a report released on Wednesday, the Scottish Parliament’s Finance and Constitution Committee says the governments have reached a “clear impasse” on the meaning and operation of the Sewel Convention.

The rule establishes that Westminster should not legislate on matters devolved to Scotland without the consent of Scottish parliamentarians.

In the newly published paper, the committee says the UK-wide legislation, which is currently before the House of Lords, raises “significant questions” that must be answered. These include the future role of devolved parliaments in fundamental areas such as trade negotiations.

Scottish ministers have already expressed fears about “restrictions” placed by the London legislation on the Edinburgh parliament’s powers.

And unless fresh agreement can be made, MSPs should not agree to back the UK Trade Bill on post-Brexit business, it is claimed.

Committee convener Bruce Crawford said: “This committee believes that the impasse between the Scottish Government and the UK Government in relation to the Sewel Convention needs to be addressed as a matter of urgency.

“We are not able to recommend that the Scottish Parliament consents to the Trade Bill unless those parts of the Bill which currently constrain the powers of Scottish Ministers in devolved areas are removed.

“Our intention is to write to the Secretary of State for Scotland and the Cabinet Secretary for Government Business and Constitutional Relations requesting that they seek a solution to the impasse over the Sewel Convention as a matter of urgency.

“We also intend to take further evidence on this issue with a view to exploring possible solutions.

“That includes examining the proposal by our Westminster counterparts for the UK Government to set out a clear statement of circumstances under which legislative consent is not required by the Sewel Convention.”

The UK Government is on record as stating that it is “fully committed” to the Sewel Convention.

However, it says the rule has never meant Scottish, Welsh or Northern Irish bodies “have a veto over ... the UK Parliament’s ability to make laws for each of the devolved nations”.

On the UK Trade Bill terms, Crawford added: “We’ve heard conflicting views from witnesses on whether or not substantive changes to existing trade arrangements will be required in the coming months.

“Either way, it is very disappointing that the Bill is silent on the role of the devolved institutions in the negotiation of the new trade arrangements.”