The public service commission has refused to release records of its boss John Lloyd's contacts with right-wing think tank the Institute of Public Affairs, despite questions about his links to the group.
After Mr Lloyd agreed in an October Senate estimates hearing to take on notice requests for phone records of his contacts with the IPA, the Australian Public Service Commission said it wouldn't release them to senators because it would involve an "unreasonable diversion" of its resources.
"In addition, it would include the release of personal information that would breach the privacy of Mr Lloyd and the people he has phone contact with," the commission said.
However the commission confirmed in a response last month he met with an IPA representative in April 2015 after sending it an email saying Labor senator Penny Wong had "taken a swipe" at two of the think tank's former directors.
The commission told Fairfax Media on Monday that the meeting had no connection to the commissioner's role, and no notes were kept.
When asked about resources needed to provide the phone records to senators, it said the work would "divert staff away from urgent priority work."
Senators questioned Mr Lloyd's IPA links after the public service commission faced criticism over new social media rules against public servants revealing their political opinions.
Workers may face disciplinary action over a private email or for 'liking' a social media post.
Community and Public Sector Union acting national secretary Michael Tull said it was dismayed but not surprised that Mr Lloyd would not release details of the number and frequency of telephone calls between his office and the IPA.
"What has he got to hide? It's extraordinary hypocrisy for Mr Lloyd to claim his privacy is threatened, given his hardline approach to the privacy and rights of other public sector workers," he said.
"It's critically important that the APSC is apolitical, just as the commission regularly reminds workers in other Commonwealth agencies that they must be."
Mr Lloyd's emails to the IPA raised serious questions about the use of APSC resources and called into question whether the commission's boss adhered to the APS Code of Conduct, making it appropriate for senators to seek further information, Mr Tull said.
Labor senator Jenny McAllister said Mr Lloyd had established onerous requirements for all other public servants to comply with in relation to their public and private comments.
"Given that imposition on other public servants, it is totally unacceptable that Mr Lloyd refuses to be upfront about his own conduct," she said.
The public service commission said Mr Lloyd's email correspondence with the IPA, and his meeting with the institute, upheld the APS value of impartiality.
During an October Senate estimates hearing, Mr Lloyd defended his link to the group and denied suggestions he gave it special access and research during a barrage of questioning by Labor senators.
They also raised an email he sent to a member of the IPA with an attachment showing generous provisions in public service enterprise agreements.
Mr Lloyd rejected a suggestion at the hearing from Labor senator Kimberley Kitching that he provided the think tank "special access" or research, saying the information he sent was publicly available.
"My sense of it is there's nothing untoward there," he said.
Before the Abbott government appointed him APS commissioner in 2014, Mr Lloyd was the director of the IPA's work reform and productivity unit.