Scottish Tory leader Ruth Davidson was greeted with calls of "shame" from rival MSPs after she refused to condemn the UK government's so-called "rape clause".
First Minister Nicola Sturgeon challenged Ms Davidson not to "pass the buck" on the child tax credit reform.
Ms Sturgeon asked her whether she agreed it was "utterly abhorrent".
Ms Davidson responded: "If the first minister doesn't like the two-child tax policy, she can change it."
MSPs in the Scottish Parliament shouted "shame, shame" and Ms Sturgeon responded: "Shame on Ruth Davidson and shame on the Conservatives."
Welfare reforms introduced by the UK government earlier this month cut child tax credit and Universal Credit for third or subsequent children.
A number of exemptions to the new rules are in place, including;
- adopting children
- those involved in kinship care
- multiple births
- and non-consensual pregnancy.
The so-called "rape clause" means women who were the victim of rape or conceived while in a coercive relationship will have to declare that their third child was born as a result of this in order to qualify for an exemption.
Ms Sturgeon, speaking during fierce exchanges at First Minister's Questions in Holyrood, added: "We have just seen in this chamber the true colours of Ruth Davidson and the Conservatives.
"Given the opportunity to stand up clearly and join others in this chamber and say the rape clause - a clause that forces a woman to prove she has been raped before claiming benefits for her child - is morally and in principle wrong, Ruth Davidson refuses to do so.
"That is utterly shameful."
The exchanges took place as protesters against the policy gathered outside the Scottish Parliament.
They were joined by politicians including Ms Sturgeon, Scottish Labour leader Kezia Dugdale, Lib Dem leader Willie Rennie and Scottish Greens MSP Alison Johnstone.
Ms Dugdale said: "This shameful and abhorrent policy must go. When people claim that Ruth Davidson is a different kind of Tory, we now know that is not the case.
"She is just as bad as all the other right wing Tories who want to force rape victims to fill out a form so they can get support from the government."
The UK government requires a non-consensual conception form to be filled in, which is a declaration by the claimant and by a third-party professional, such as a doctor or social worker, that the terms of the exemption have been met.
Speaking to the BBC's Good Morning Scotland programme earlier on Thursday, Scottish Conservative deputy leader Jackson Carlaw accused opponents of the rape clause of spreading a "tremendous amount of misinformation" about it.
And he insisted the clause was designed to give additional support to children who had been conceived as the result of a rape.
Mr Carlaw said: "There is no requirement for anybody to fill out an eight-page form. They simply have to declare to their GP or another health professional that that was the circumstance in which they had conceived the child.
"That will then allow the additional support to come to them.
"It is not about them having to prove anything, it is not about them having to go through some sort of means-tested inquiry".