A "grubby deal" between Conservatives and the Democratic Unionist Party is not in the national interest, Nicola Sturgeon has said.
The First Minister said she is concerned by the "disregard" shown for the Northern Irish peace process and called for full details of any deal to be made public.
Speaking at First Minister's Questions, she said: "I want to record my deep-seated concern and, I believe, the deep-seated concern of many not just in Scotland but across the UK right now at the prospect of some sort of grubby deal between the Tories and the DUP to allow Theresa May to cling to office.
"I don't think that kind of deal, particularly if it is not completely and utterly transparent, is in the national interest in any way, shape or form.
"I say that not just because of some of the views of the DUP that, perhaps not all of us, but many of us feel deeply uncomfortable about, but I also say that because of a real concern about the disregard that is being shown for the Northern Irish peace process.
"I think one of the most shameful aspects of the whole Brexit process from the beginning to now has been the disregard shown by many for that peace process."
She said there is a real question about whether the UK Government could be an impartial broker in the peace process as outlined by the Good Friday Agreement.
She added: "I've seen this morning some suggestion that the deal, if there is a deal, between the Tories and the DUP will not be published in full. I think that would be completely unacceptable."
The SNP's James Dornan asked the First Minister if she shares his concern about the message a deal between the Conservatives and the DUP, who have used their veto to block legalising same-sex marriage in Northern Ireland five times, sends to the LGBTI community.
Ms Sturgeon said: "I do think it is regrettable that Northern Ireland is the only part of the UK where loving same-sex couples cannot get married as they can in England, Wales and Scotland and I certainly would hope to see that change for the better in the not too distant future".
She said the issue of same-sex marriage in Northern Ireland would be decided by politicians there.
A Scottish Conservatives spokesman said: "Even for the SNP, Nicola Sturgeon's attack on the Conservative talks with the DUP takes hypocrisy to new levels.
"It is only three years since Alex Salmond made it clear that the SNP would work with the DUP, and Sinn Fein, at Westminster. Now Nicola Sturgeon claims such a deal is 'grubby'.
"As usual with the Scottish nationalists, it is one rule for them and another rule for everyone else. It is double standards like this which is turning off Scots in their thousands."