A report into a computer hack at Parliament House might not be released, even in redacted form, Senate president Scott Ryan says.
Senator Ryan received the report last week and read it on Friday but has now told an estimates hearings it is highly technical. He needed to take advice to ensure he understood it correctly before divulging any of its contents.
Even then, he would not necessarily release the report, he said.
Prime Minister Scott Morrison has already attributed the hack to a sophisticated state actor, and China has been implicated in the media.
But Senator Ryan would not say even whether a foreign government was believed responsible, let alone which one if so.
Under questioning from crossbench Senator Rex Patrick, he insisted that information was not "appropriate for public consumption".
But he said he would consult lower house Speaker Tony Smith.
Senator Patrick had a string of questions about the hack, including whether security services had been given access to the parliamentary IT system during their investigation and if so whether that access had been supervised.
He also wanted to know whether there was any evidence that an insider with authorised access to the parliamentary system had been involved. He asked whether the hack had used the same "spear phishing email" technique by which the Australian National University network had been hacked, when the hack began and how long it lasted. Senator Ryan took the questions on notice.
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The attempt to hack into parliament's computer network was in February. It coincided with an attack on the computer systems of the Liberal, National and Labor parties.
Parliamentary authorities said in February there was no evidence any data had been accessed or taken in the parliamentary hack, but passwords had been changed.
Senator Patrick called for the kind of transparency shown by the ANU, which published a detailed account of how the hackers gained entry and what they did once inside the university's network.
Senator Ryan said he agreed with the ANU's approach. But having read the investigators' report into the hack, he was not convinced it would be appropriate for publication, even redacted.
Separately, Senator Ryan revealed he was considering making the no-fly zone above Parliament House permanent.
The Greens' attempt to fly a "climate emergency" balloon during a protest last week was torpedoed by Senator Ryan, who applied to the Civil Aviation Safety Authority for the no-fly zone within 460 metre radius.
The Greens Senator Larissa Waters took a photograph on Monday of a balloon flying over Parliament House despite the no-fly zone. Asked why it had been allowed, Senator Ryan said enforcement was for CASA.
CASA spokesman Peter Gibson said the agency did not approve or monitor each flight and would only review if it received a complaint or information of a possible breach.
Senator Ryan said he would have sought to ban the balloon last week whether or not it was for a climate protest, insisting there "shouldn't be a free for all".
Department officials said all balloon flights must lodge a flight plan but given that balloons were subject to wind their trajectory could not always be controlled. They would be surprised if the balloon had been allowed to fly over Parliament House, the officials said.