Nicola Sturgeon has accused UK ministers of using trans people “as a political weapon” if the Tory Government challenges Scotland’s gender recognition reforms.

The UK Government is pondering using section 35 of the Scotland Act to block the Holyrood legislation, overwhelmingly backed by MSPs last month – with members of all parties including the Conservatives voting in favour of the legislation.

The Bill will allow trans people to obtain a gender recognition certificate (GRC) without the need for a medical diagnosis — a process known as “self-identification”.

It will also permit 16 and 17-year-olds to apply for a GRC for the first time, and would reduce the amount of time a person has to live in their acquired gender before they can be granted the document.

Ministers have until Wednesday to launch the unprecedented move which has never been used in devolution, but a decision could come as soon as today according to reports.

Read More: Gender reform: Rishi Sunak faces Wednesday on blocking Scotland’s GRC

Multiple reports have suggested that the legal advice the UK Government has received will provide the Prime Minister with the cover he requires to the action.

If he does so, he will become the first No 10 incumbent to use the blocking mechanism.

The Scotland Act gives Westminster four weeks to consider bills passed by Holyrood that could have an “adverse effect on the operation of the law”.

Ahead of the deadline expiring, the First Minister insisted she will “absolutely, robustly and rigorously” defend the legislation, adding that her government has “a very high degree of confidence” that the reforms are legally sound.

Read More: Rishi Sunak warns gender reforms may have 'impacts across the UK'

Ms Sturgeon was asked about the potential clash with Westminster at her news conference on the NHS.

She warned it “would be an outrage” if the UK Government did attempt to block the reforms using a mechanism that “has not been used in almost a quarter of a century”.

Ms Sturgeon added: “There are no grounds to challenge this legislation within the competence of the Scottish Parliament.”

The First Minister pointed to the Bill being “passed by an overwhelming majority of the Scottish Parliament…by MSPs of all parties”.

She added: "So if there is a challenge to decision, in my view it will be quite simply a political decision and I think it will be using trans people - already one of the most vulnerable groups in our society - as a political weapon.

"I think it will be unconscionable and indefensible and really quite disgraceful."

A UK Government source said "the First Minister's claims are completely wrong".

They added: "The UK Government has been clear that any response to the Scottish Government's Gender Recognition Reform Bill would be based on concerns about its impact on UK-wide legilsation and follow procedures set out in the Scotland Act."

Read More: Starmer expresses 'concerns' over aspects of Scots gender law reforms

Yesterday, UK Labour leader Keir Starmer warned he was not convinced the gender reforms should be extended to 16-year-olds, despite his party at Holyrood backing the legislation.

Ms Sturgeon said that it is valid to “start to wonder if there is anything Keir Starmer is willing to stand up and be counted” for in response to “Tory attacks” on democracy.

She stressed that the proposals have been “scrutinised and voted for by Keir Starmer’s own party in the Scottish Parliament”.

The FM added: “If he backed any move…he would be showing utter contempt for his own party as well as the Scottish Parliament.”