The clash unfolded after a question from opposition education spokesman Liam Staltari about what the minister acknowledged were "AI mistakes" in the Deloitte report being used by the Cook government to justify the merger.
In his response, Buti said Zempilas had offered his support for a three-way merger during a private conversation in Parliament House six months ago.
"[Zempilas] said to me, 'My personal view is that I agree with a three-way merger'," Buti told parliament. "Not only that, he said, 'I know your side won't agree, but can I stand by you when you make the announcement?'"
The chamber erupted as Zempilas yelled "You are a liar" and "You are a joke" multiple times across the chamber. Speaker Stephen Price called him to order twice, and Zempilas was required to withdraw the "liar" comment, which he did. He later yelled it multiple times again.
"No wonder you can't get anything right," Zempilas yelled.
As Price scolded Zempilas, he was told he could make a statement after question time to correct the record. The confrontation has sharpened what was already a bitter fight over the proposed mega-university, with Curtin University publicly opposing the plan.