Scottish Conservative leader Ruth Davidson said she has received assurances from the Prime Minister over gay rights should the Tories do a deal with Democratic Unionist Party.
Ms Davidson, who is openly gay, spoke out after Theresa May outlined a plan to seek a deal with the socially hardline party, which has 10 seats in the Commons, to prop up her minority administration.
She raised concerns with British Prime Minister Theresa May over the DUP's controversial stance on gay rights.
The party opposes gay marriage, meaning Northern Ireland is the only part of the UK where gay couples can't wed.
Ms Davidson plans to marry her Irish partner in the near future.
Speaking this evening to the BBC's 'Reporting Scotland' programme, she said the Prime Minister had given her assurances there would be no effect on gay rights in the UK should a government be formed with the DUP.
Ms Davidson said: "I was fairly straightforward with her and I told her that there were a number of things that count to me more than party.
"One of them is country, one of the others is LGBTI rights."
She said Mrs May had given her a "categoric assurance" that there would be "absolutely no rescission of LGBTI rights in the rest of the UK."
She added that Mrs May had agreed to use her influence to try and advance gay rights in Northern Ireland.
In a tweet sent on Friday afternoon, Ms Davidson highlighted a speech she made in Belfast about the importance of equal marriage.
She said in the speech: "I am a practising Christian - I care deeply about the role of the church in the public realm.
"I believe passionately that it is a force for good.
"I might not always agree with every intervention churches make in politics, but I defend their right to do so.
"In Scotland, we made sure that as we passed equal marriage, we also protected the rights of religious groups.
"We owe it to those who take an opposing view to engage and explain, to discuss and persuade.
"You don't effect change by shouting down your opponents, whose votes you need."
She added that legalising same-sex marriage in Northern Ireland would "make every couple in this country equal in the eyes of the law".
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 the MP son of Dr Paisley, Ian Paisley Jr, said he felt "repulsed" by homosexual acts.
A party councillor in Ballymena reportedly claimed Hurricane Katrina, which killed more than 1,500 people in the US, was God's revenge for New Orleans hosting an annual gay pride event.
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.
In the 2015 general election campaign, DUP health minister Jim Wells resigned amid a controversy about remarks he made about same sex couples.
Then prime minister David Cameron said he would "never validate" the DUP's position on gay rights while deputy PM Nick Clegg claimed some of the party's views were "backwards".
Last year, DUP Stormont MLA Trevor Clarke admitted he thought only gay people could contract HIV.
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."
An online petition in objection to the Tories and DUP forming a minority government has gathered more than 300,000 signatures.
FIANNA Fáil leader Micheál Martin accused Sinn Féin of letting down their electorate by not taking their seats in Westminster and allowing the DUP to be the sole voice for Northern Ireland in the UK parliament.
The big question is what the result means for Brexit. Bizarrely, from an Irish perspective, Brexit wasn't that big an issue during the UK campaign - although a massive turnout of younger voters in support of Labour was probably a knock-on affect from last year's vote.