ABC producers tried to contact two people familiar with former terror suspect Zaky Mallah before allowing him to ask a question live on air because of concerns about his suitability, an Abbott government review has found.

But the last-minute efforts were unsuccessful, meaning the Q&A team had to rely on its previous experience with Mr Mallah, the advice of a journalist, past interviews and some of his social media posts. The social media review did not uncover sexist tweets about female journalists which the ABC has said would have ruled Mr Mallah out of appearing on the program.

Fairfax Media understands Q&A only began considering Mr Mallah to ask a question on the day of the controversial broadcast, just hours before it went to air, meaning there was little time to check his suitability.

It is understood producers attempted to contact counter-terrorism expert Anne Aly, who appeared as a panellist on this week's episode of Q&A, to check whether Mr Mallah was suitable to ask a live question.

ABC management and the ABC board have since conceded it was an "error of judgment" to allow Mr Mallah to ask a question in a live, uncontrolled environment. Q&A's executive producer Peter McEvoy has been given an official misconduct warning for not referring the decision higher prior to broadcast.

The review, conducted by the Department of Communications, also confirmed that Mr Mallah had attended Q&A as an audience member before.

The department released a three-page summary of its investigation on Friday, with the section on the program's security arrangements redacted for safety reasons. The review is essentially a chronology of the circumstances leading up to the broadcast and does not contain recommendations for the ABC.

The review found Mr Mallah, who in the past pleaded guilty to threatening to kill officers of ASIO or DFAT, was "was well known to the Q&A editorial management team" before his June 22 appearance.

"He had first registered to be an audience member in 2011, had attended Q&A as an audience member on two occasions and been booked as an audience member on another three occasions but cancelled his booking on the day of the broadcast," the review found.

"He has also asked to be a panellist on the program on two occasions; neither time has he been accepted. On one other occasion he was asked if he wished to attend in the audience but did not accept the invitation."

It is only when Mr Mallah was being considered to ask a question live-on-air that any checks on him were undertaken for the June 22 episode.

"After attempts to contact two people familiar with Mr Mallah were unsuccessful, the Q&A team relied on its previous experience with Mr Mallah, the advice of another ABC journalist, a review of a recent television appearance and a review of his social media posts undertaken in August 2014, which did not include Mr Mallah's offensive tweets [about two female journalists] posted in early 2015 or his recent YouTube videos, in determining that he was not dangerous, would not be disruptive and would be a suitable audience member to ask a question," the review found.

The review found Mr Mallah had made extensive media appearances in the past, including on commercial television, print media and radio.

The review also canvassed the rebroadcasting of the episode two days after it originally went to air. At the time Prime Minister Tony Abbott said the ABC had "compounded that terrible mistake, that betrayal, if you like, of our country … by rebroadcasting the program" and called for "heads to roll" at the ABC.

The ABC advised the Department it rarely withdraws or edits a program prior to repeat, usually only if there are known legal concerns or formal editorial content breaches identified in a program.

Instead, it rebroadcast the controversial episode of Q&A with an advisory warning.

The review finds the ABC received 962 audience complaints about the broadcast. It is understood the ABC has also logged over 900 messages and calls of support.

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