ABC managing director Mark Scott was grilled by several MPs on Wednesday on the network’s judgment in letting former terror suspect Zaky Mallah throw questions at a Q&A panel.

The ABC had previously admitted it was an “error of judgment’’ to allow ASIO target Mallah on Monday night’s show on, and the decision was being examined as part of an independent review.

But Mr Scott refused to comment on the issue when questioned by reporters in Canberra on Wednesday.

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It was found that Mallah, along with about 40 others, was a passenger on a shuttle bus the ABC provided free of charge to get people from western Sydney into their studios in Ultimo in Sydney, News Corp reported.

Zaky Mallah in the Q&A audience.

An ABC spokesman on Wednesday issued a brief statement to New Corp that read: “Every Monday night Q&A provides a free bus service from western Sydney for audience members attending the show”.

“This week Zaky Mallah was a passenger on that bus.”

On Monday night Mallah questioned Liberal MP Steve Ciobo on the Q&A program about proposed changes to citizenship laws.

Appearing as a vetted questioner in the audience, Mallah said Australian Muslims were justified to travel to Syria to join Islamic State (ISIL).

Mr Scott met Communications Minister Malcolm Turnbull later on Wednesday, after the MP labelled the ABC’s decision a “very grave error of judgment”.

One MP, Nationals Member for Mallee Andrew Broad, lost a cousin in the Bali bombing terror attacks in 2002, and questioned Mr Scott in the briefing.

According to News Corp, Mr Broad asked Mr Scott to take MPs concerns more seriously, and reflect on the seriousness of allowing Mallah a platform.

“We had a respectable and decent conversation about the personal impacts of terrorism,’’ Mr Broad said.

Disgruntled Liberal MP George Christensen called for the ABC’s free bus service to be scrapped.

MP Andrew Broad quizzed Mr Scott in the briefing. Photo: AAP

Meanwhile, Defence Minister Kevin Andrews has vowed to boycott the ABC’s Q&A program, and was the first Abbott Government minister to officially blackball the show.

He encouraged his colleagues to do the same, The Australian reported.

Prime Minister Tony Abbott on Wednesday redoubled his attack on the national broadcaster, accusing it of “unacceptable” behaviour for rebroadcasting Monday night’s controversial episode.

“The ABC has compounded this problem by again airing this disgraceful individual’s views,” Mr Abbott told Fairfax Media.

“This is unacceptable. The ABC has once again given a platform to someone who hates us, who hates our way of life, who supports terrorists, and again, I ask of the national broadcaster: whose side are you on?”

News Corp reported that Mallah was briefed by an experienced Q&A executive producer, had dealings with a floor supervisor, and was contacted by at least one other producer to discuss his proposed questions, prior to the show.

– with AAP