THERESA May’s de-facto deputy has failed to respond to an “urgent” call from ministers in Edinburgh to come to Holyrood to try to end the dispute over Brexit powers.

Michael Russell, the Scottish Brexit Minister, wrote to David Lidington on May 15 – the same day that the Scottish Parliament voted formally against the UK Government’s EU Withdrawal Bill.

However, he told MSPs yesterday: “More than a week after that letter I still haven’t received any reply at all.”

He spoke out at the same time as it emerged Scottish Trades Union Congress (STUC) general secretary Grahame Smith had written to the Prime Minister, urging her to strike an agreement that “respects our devolved institutions”.

After last week’s vote, in which SNP, Labour, Green and LibDem MSPs all refused to give formal approval to the UK legislation, Russell called on Lidington – who has been leading talks with the devolved administrations over the Withdrawal Bill – to come to Scotland and hear their concerns.

SNP MSP Mairi Gougeon said the failure to reply by the UK Cabinet Office Minister was an example of the “complete lack of respect shown to this Parliament” by Westminster.

Russell added: “I really do think it is time that the UK Government paid some attention to the democratic legitimacy of this chamber and of this government, and negotiated with it.”

The long-running dispute centres on what should happen to powers currently held by Brussels after the UK leaves the EU. Scottish Government ministers insist that the bill in its current form could restrict Holyrood’s powers for up to seven years after Brexit.

Smith stressed it would be “simply not acceptable” for Westminster to be able to legislate in areas devolved to Holyrood. He said: “Arrangements that allow the UK Government to legislate on areas of devolved competence – without the agreement of the Parliament elected by the Scottish people to serve their interests – is simply not acceptable.”