A Conservative peer has argued for the UK Government to block Holyrood’s gender recognition legislation.

Lord Keen of Elie, a former advocate general for Scotland, said the Bill would impact the operation of the UK-wide Equalities Act 2010 and therefore be open to a legal challenge.

However, his comments came as a coalition of 145 leaders from LGBT groups wrote to the Prime Minister urging him not to take the step.

MSPs, last month, passed the Gender Recognition Reform (Scotland) Bill by 86 votes to 39, approving reforms which would allow trans people to obtain a gender recognition certificate (GRC) without the need for a medical diagnosis.

Pride Glasgow 2017
LGBT groups said the Bill should not be challenged (David Cheskin/PA)

The Scottish Government says it will “vigorously” contest any moves to challenge the Bill under the Scotland Act.

The UK Government says it has “concerns” over the Bill but is yet to announce a decision on whether they will seek to stop it from becoming law.

Lord Keen referred to a report from the conservative Policy Exchange think tank, saying Scottish ministers had been “contradictory” on the legal implications of their Bill.

The report, authored by Glasgow University law lecturer, Dr Michael Foran, argued the case for section 35 of the Scotland Act to be used – blocking Royal Assent.

Scottish Parliament citizens panel
MSPs voted for the Bill at the end of last year (Jane Barlow/PA)

He said it would change the meaning of “sex” under the Equality Act for the whole UK and have implications for single-sex spaces.

Supporters of the Bill have always denied this would be the case.

Lord Keen said: “It would not only be impractical but constitutionally improper for the UK Government to permit a devolved legislature to enact a provision that had a material impact upon the operation of the law throughout the United Kingdom.

“The immediate concern identified by Dr Michael Foran is the potential impact of the Scottish Government’s gender recognition legislation upon the operation of the Equalities Act 2010, an Act which clearly addresses issues reserved to the UK Government and which operates throughout the UK.

“Such concerns were voiced during the passage of the Bill in the Scottish Parliament.

“It is therefore unfortunate that the position of the Scottish Government has remained opaque and, at times, contradictory.”

Meanwhile, a letter from the LGBT Consortium noted that there had been years of debate and scrutiny around the Scottish Bill.

The consortium, which includes the charity Stonewall, said any challenge would not be based on evidence or experience.

Their joint letter said: “It sends a clear message that the UK Government does not feel trans people are worthy of respect in our society; instead, they are a threat to contain.

“These moves also directly oppose the inclusive values that characterise modern Britain and will actively harm the UK’s international reputation as an open, diverse and dynamic society – an important reason why global corporations who proudly support LGBTQ+ rights are attracted to doing business in the UK.”

A Scottish Government spokesman said: “The Bill as passed is within legislative competence, and was backed by an overwhelming majority, with support from members of all parties.

“Any attempt by the UK Government to undermine the democratic will of the Scottish Parliament will be vigorously contested by the Scottish Government.

“We have always been clear that the Bill does not impact on the Equality Act, and the Bill as passed puts that position beyond doubt.”