Malcolm Turnbull has absolved his employment minister, Michaelia Cash, of any responsibility for the controversial appointment of Nigel Hadgkiss as head of the building industry watchdog, saying Hadgkiss was appointed by an act of parliament, not by Cash personally.

Labor is now ramping up calls for an inquiry, and the Greens are backing it.

The Turnbull government is under increasing pressure to explain why it allowed Nigel Hadgkiss to become commissioner of the Australian Building and Construction Commission (ABCC) last year when it knew he had been accused of breaching workplace laws during his earlier tenure as head of the Fair Work Commission’s building and construction office.

Hadgkiss became head of the ABCC after last year’s election, when it was re-established by the Coalition, but resigned last week after admitting in court to contravening workplace laws in 2013.

Cash told the Senate last week that she first became aware of complaints against Hadgkiss in October last year, even though court proceedings had been instituted against him two months earlier.



She also conceded that she did not stop Hadgkiss becoming ABCC commissioner even though she knew he had been accused of breaking the law.

Labor is now calling for an independent inquiry into Hadgkiss’s appointment as ABCC commissioner, which the Greens are supporting.

“How is it acceptable that, as a cabinet minister, Michaelia Cash could be aware of legal proceedings against her hand-picked regulator based on his deliberate misrepresentation of the law he was charged to uphold, and wilfully turn a blind eye?” Labor employment spokesman, Brendan O’Connor, said on Monday.

“Minister Cash must explain whether and when she informed the prime minister and cabinet about the legal proceedings that were on foot against Mr Hadgkiss, that were so serious they led to his admission that he broke the law for two and a half years, and ultimately to his resignation.

“If she did inform them, then why did the prime minister and cabinet appoint Mr Hadgkiss to the new body that was established after the double-dissolution election?

“If she didn’t inform them, how can Michaelia Cash possibly claim to have satisfied her ministerial obligations under the cabinet handbook, which required her to disclose any sensitivities about the appointment?”

Adam Bandt, the Greens industrial relations spokesman, told Guardian Australia an inquiry into Hadgkiss’s appointment was appropriate.

But Turnbull absolved Cash on Monday, saying Hadgkiss had been automatically appointed to head the ABCC last year without Cash’s direct involvement.



“Mr Hadgkiss became the ABCC commissioner by virtue of an act of parliament because he was already the commissioner of the Fair Work Building Commission which then transformed into the Australian Building and Construction Commission,” Turnbull said.

Turnbull also said it was “public knowledge” that legal proceedings had been initiated against Hadgkiss before he was appointed as ABBC commissioner last year, which Labor has jumped on.

O’Connor said Turnbull’s admission contradicted Cash’s version of events.

“The prime minister’s admission reveals the truth – that the government reintroduced the ABCC legislation, knowing that it would result in Mr Hadgkiss becoming commissioner, and they did nothing to prevent it,” O’Connor said.

“Why did the minister push the ABCC legislation through the parliament, requiring that Mr Hadgkiss was appointed as ABCC Commissioner, despite knowing the behaviour that Mr Hadgkiss had engaged in?

“This is a scandal and nothing short of an independent inquiry will do.”