Scottish Conservative leader Ruth Davidson said she has received assurances from the prime minister over gay rights should the Tories do a deal with the Democratic Unionist Party.
Ms Davidson, who is gay, spoke out after Theresa May outlined a plan to seek a deal with the socially hardline Northern Irish party, which has 10 seats in the Commons, to prop up her minority administration.
In an apparent criticism of the plan, Ms Davidson on Friday tweeted a link to a speech she made in favour of marriage equality, with the message: "As a Protestant Unionist about to marry an Irish Catholic, here's the Amnesty Pride lecture I gave in Belfast. "
Ms Davidson, who became engaged to partner Jen Wilson in May 2016, later told the BBC: "I was fairly straightforward with her [Ms May] and I told her that there were a number of things that count to me more than the party.
“One of them is country, one of the others is LGBTI rights.
"I asked for a categoric assurance that if any deal or scoping deal was done with the DUP there would be absolutely no rescission of LGBTI rights in the rest of the UK, in Great Britain, and that we would use any influence that we had to advance LGBTI rights in Northern Ireland.
“It’s an issue very close to my heart and one that I wanted categoric assurances from the prime minister on, and I received [them].”
Petition of concern
Northern Ireland is the only part of the union where same-sex marriage remains outlawed.
The DUP has repeatedly used a controversial Stormont voting mechanism – the petition of concern – to prevent the legalisation of same-sex marriage, despite a majority of MLAs supporting the move at the last vote.
The party has often found itself embroiled in controversy over its stance on gay rights issues.
Founded on the evangelical principles of the late Ian Paisley’s Free Presbyterian church, the party has been repeatedly at odds with the North’s LGBT community.
While the party insists it is protecting the “traditional” definition of marriage, critics have denounced its stance as homophobic.
Going back decades, the DUP was at the vanguard of the failed Save Ulster from Sodomy movement that campaigned against the 1982 legalisation of homosexual sex in Northern Ireland.
In more recent times, former first minister Peter Robinson's wife Iris, then an MP, described homosexuality as an "abomination", while Ian Paisley jnr said he felt "repulsed" by homosexual acts.
Former DUP Stormont minister Edwin Poots once hit out at a gay rugby team in Belfast, accusing it of introducing a sporting "apartheid" against heterosexual players.
Mr Poots also ended up in court for upholding a ban on gay men giving blood and, in a separate case, objecting to gay couples adopting. In the former case an appeal judge overturned a finding that he was motivated by bias.
Defending her party's stance on gay marriage in a recent interview, leader Arlene Foster insisted those who characterised the DUP as anti-gay were wide of the mark.
“They are wrong and they need to understand why we take those positions from a faith point of view and why we want to protect the definition of marriage,” she said.
“I could not care less what people get up to in terms of their sexuality, that’s not a matter for me, when it becomes a matter for me is when people try to redefine marriage.”
PA