Lawyers assisting the trade unions royal commission have called for a recommendation of criminal charges against former CFMEU Queensland president Dave Hanna and two former executives of developer Mirvac over corrupt payments.

The barristers have made a submission that Mr Hanna, along with Adam Moore and Mathew McAllum, may have committed offences under state laws relating to secret commissions, which carry penalties of up to seven years' jail.

It was alleged in the inquiry Mr Hanna — in his previous role as Builders Laborers Federation Queensland secretary— had received $150,000 of free work on his new luxury home at Cornubia, south of Brisbane, that Mirvac ultimately paid for.

The inquiry heard the payments were disguised by being attributed to a Mirvac-built shopping centre at Springfield, 30 kilometres away.

"David Hanna received the free goods and services knowing they were being given in the hope or expectation that he would not exercise [or refrain from exercising] his powers as a union official in a manner, adverse to Mirvac, Adam Moore and Mathew McAllum," the submission stated.

The lawyers said there was insufficient evidence to recommend a similar finding in relation to Mirvac itself.

The affected parties will be given a chance to respond to the submissions.

It will be up to the commission — headed by former High Court judge Dyson Heydon — to decide whether to take up the call to recommend charges.

Questions raised over whistleblower

Separately, counsel assisting the commission has cast doubt on the credibility of a key construction industry whistleblower whose claims of union corruption helped spark the inquiry.

Andrew Zaf told the inquiry that in 2014, CFMEU Victoria boss John Setka had used intimidation to obtain free building materials and made Mr Zaf employ people as a favour to the union.

The claims echoed allegations Mr Zaf made on ABC's 7.30 in January 2014.

The commission left the section on Mr Zaf's claims blank in its interim report in December after his evidence was called into question just before it was published.

Last month a former business partner of Mr Zaf's, Gary Cheetham, gave evidence that Mr Zaf had made up many of his claims.

He alleged Mr Setka had not received a roof on his house for free, as alleged by Mr Zaf, but at cost.

Mr Cheetham even claimed Mr Zaf had stabbed himself with a stanley knife to discredit the CFMEU.

In their submission on Friday, counsel assisting told the inquiry: "Whilst in many ways Gary Cheetham's evidence was unsatisfactory and his demeanour unconvincing, some aspects of his evidence are supported, at least to an extent."

The barristers also pointed to evidence from Victoria police that suggested the possibility Mr Zaf's injuries were self-inflicted.

"Given the impact that this has had on Andrew Zaf's credibility ... it is submitted that no positive submission based on Andrew Zaf's evidence can now be maintained."

CFMEU calls for an apology

CFMEU national construction division secretary Dave Noonan said the counsel assisting had been "dragged kicking and screaming to the truth".

In a statement, Mr Noonan claimed Mr Cheetham contacted the CFMEU after his approaches to the commission and the media were ignored.

"Counsel assisting was instead proposing to make serious findings against Mr Setka based on Zaf's evidence in his draft submissions released in October of 2014," Mr Noonan said in the statement.

"This clearly demonstrates the deep bias against the CFMEU by the commission.

"John Setka has had his name smeared by Liberal politicians off the back of these fanciful allegations, which were allowed to stand untested for so long.

"John Setka deserves an apology from the Liberal Party's royal commission, from Fairfax, Nick McKenzie and from ABC's 7.30 report."