'How dare you': Karl Stefanovic unleashes on Diana's former butler

Karl Stefanovic has skewered Princess Diana's former butler on live television for claiming Kate Middleton doesn't have "the X factor".

The Today host didn't hold back, opening the awkward interview by asking Paul Burrell whether his comments about the Duchess of Cambridge were "way too harsh".

Diana's former butler apologised and said his comments had been taken out of context, but Stefanovic was having none of it.

"Everyone wants to see what she is doing and she doesn't put a foot wrong," he said. "How dare you even say that."

Burrell tried to back pedal, saying his X-factor comment was meant to be about how Diana was larger in life and no one could possibly replace her.

"You see, standing beside someone like Diana I saw something so special and so magical that I can't - I have never seen that," he said.

"How often have you stood beside Kate?" Stefanovic shot back.

"I haven't," Burrell admitted. "I don't know Kate. I just see her the way you see her, through a lens."

Stefanovic then went for the jugular, telling the former butler his excuses were "ridiculous" and for him to imagine what he would say to Prince William if he asked about what he meant.

"Why don't you leave Kate alone?" he said. "Do you have some sort of oxygen deprivation at the moment? I mean, come on. She is a mother of two doing the very best she can. She's awesome."

Wednesday morning's interview was Stefanovic's second epic rant in just two days. On Tuesday, he took the government to task over its plans to once again push for a multi-million dollar plebiscite on same-sex marriage instead of simply holding a free vote in parliament.

"A non-binding, non-compulsory postal vote is complete BS," he said. "Why do we elect officials if not to make decisions that reflect our beliefs? Let's get on with it. Pull your fingers out in Canberra and get on with it."

While viewers heaped praise on Stefanovic for his straight-talk on marriage equality, some weren't impressed with Wednesday's combative interview.

Some Today viewers even accused the co-host of trying to manufacture a story and said he went over-the-top with his criticism.