Agriculture Minister Barnaby Joyce has played down Prime Minister Tony Abbott's decision to ban frontbenchers from appearing on the ABC's Q&A program, but says "it would have been good" to have been given more notice.

Mr Joyce last night withdrew from a scheduled appearance on tonight's program only hours after telling the ABC that he would be taking part in the show.

A spokesman for Mr Joyce confirmed the minister cancelled after being told by Mr Abbott that no frontbenchers were to appear on Q&A.

The ABC has admitted it was an "error of judgement" to allow convicted criminal Zaky Mallah into the live studio audience to question a Government frontbencher in June.

Addressing the National Press Club today, Mr Joyce said he was simply obeying his leader's instructions.

"The Prime Minister of Australia is precisely that," he said.

"It is by deference to the Prime Minister that when an instruction comes through, it is obeyed.

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"Otherwise the whole process of Cabinet becomes chaotic.

"Do I think it would have been good to know about it a little bit earlier? Yes, that would've been nice, but that's life, you take it on the chin."

On Twitter, ABC managing director Mark Scott said Mr Joyce was passing up a prime-time opportunity to promote his newly released agriculture white paper.

The Prime Minister's office released a statement saying it was "not appropriate" for Mr Joyce to appear tonight "given the ABC is undertaking an inquiry into Q&A".

That inquiry, which was announced before last month's broadcast, is being led by veteran broadcaster Ray Martin and is due to be completed later this year.

The board has also issued a formal warning to the show's executive producer.

Mr Joyce's withdrawal from the program yesterday came hours after he confirmed on the ABC's Insiders program that he would be taking part.

He said the ABC's decision to allow Mr Mallah on the program was an "absurdity" but believed the ABC was "dealing with the issue".

Turnbull should give PM the finger: Fitzgibbon

Labor frontbencher Joel Fitzgibbon said it was extraordinary for Mr Abbott to direct the deputy Nationals leader not to appear on the show, and called on Mr Joyce to stand up to him.

"This is not Soviet Russia or even modern day Korea, this is Australia, a democracy," he said.

"We've got to ask ourselves why the Prime Minister is doing this."

Mr Abbott's directive is likely to put pressure on Communications Minister Malcolm Turnbull, who is due to appear on the Q&A panel next Monday.

Mr Turnbull has previously said he did not support a boycott but knocked back an invitation to appear on Q&A last week, along with Defence Minister Kevin Andrews and parliamentary secretary Alan Tudge.

Mr Fitzgibbon has predicted Mr Turnbull will keep his commitment.

"I'd like to have $20 on Malcolm Turnbull appearing on Q&A next Monday night," he said.

"I would be amazed if Malcolm Turnbull doesn't do what Barnaby Joyce should do today and give the Prime Minister the single finger and get on with it."

A Communications Department report released on Friday found Q&A did make checks on Mallah, but had not reviewed his recent social media posts.