Queensland's corruption watchdog has ordered an investigation into "serious allegations" senior government workplace safety officers have passed confidential information to the construction union and helped its officials target a Brisbane manufacturer.

Key points: Two government officials are accused of faking an anonymous complaint so one of them could inspect a manufacturing site

Two government officials are accused of faking an anonymous complaint so one of them could inspect a manufacturing site A video shows a CFMEU official swearing at ENCO employees on a worksite last year

A video shows a CFMEU official swearing at ENCO employees on a worksite last year The CFMEU says ENCO Precast is a "rogue employer"

Two officials from Workplace Health and Safety (WHSQ) are named in the complaint, with Queensland's Crime and Corruption Commission (CCC) concluding that "the alleged corrupt conduct is of a serious and/or systemic nature".

The CCC has now directed the Queensland Office of Industrial Relations to investigate the allegations, with the watchdog vowing to review the investigation and monitor "how the matter is dealt with".

The allegations were made by the concrete bridge beam manufacturer ENCO Precast, which claimed the WHSQ officials "misused their authority and powers … in order to cause/threaten to cause a detriment" to the company.

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ENCO refused entry to CFMEU officials

ENCO Precast has been resisting Construction, Forestry, Maritime, Mining and Energy Union (CFMEU) attempts to enter its Brisbane worksite over alleged safety concerns, with the company arguing that none of its workers are members of the union and that the safety concerns are vexatious.

"We don't have any CFMEU members here," ENCO Precast general manager Steven James said.

"They [the alleged safety concerns] are very general in nature, they were access and egress, fire extinguishers, electrical concerns."

In July last year, several CFMEU officials wearing permits entered the worksite sparking a confrontation in which ENCO Precast employees called police.

"Police? Whoop-de-f***ing-doo mate. They don't get involved in industrial disputes," a CFMEU official says in a video recording of the incident.

"We've got rights to f***ing be here, we've told you that many f***ing times."

Space to play or pause, M to mute, left and right arrows to seek, up and down arrows for volume. Watch Duration: 8 seconds 8 s A CFMEU official swearing at an ENCO Precast employee.

Mr James said the union officials were being threatening.

"It was very aggressive," he said.

"There was initially around about 10 to 12 people standing across the road here and very large gentlemen who came to the site and pushed their way into the site."

In meetings, WHS officials have told ENCO Precast that the CFMEU has a right to enter the site.

CFMEU state secretary Michael Ravbar was carried into the union corruption royal commission hearing in 2014. ( AAP: Dan Peled )

In a video recorded a few days after the initial entry and seen by the ABC, WHS construction director Helen Burgess can be heard telling ENCO Precast executives that "we will be writing you a direction to allow them [the union officials] to enter".

The company was later issued five notices to let the CFMEU and other union officials come onto the site.

The CFMEU's Queensland state secretary Michael Ravbar said the company had an "abominable reputation in the industry for cutting corners … ENCO is a rogue employer which has challenged not only the legal right of authorised union officials, but also government safety inspectors, to enter its work sites to address safety concerns".

Mr James said the comments about ENCO's reputation were standard rhetoric and unsubstantiated.

Allegations WHSQ officers faked 'anonymous' complaint

In its complaint to the CCC, ENCO Precast alleged that Ms Burgess "pressured another unknown WHS officer … to lodge a false (untrue) 'anonymous' complaint about ENCO to enable [the] CFMEU" to enter the ENCO worksite last year.

The ENCO Precast building site. ( ABC News: Alexandra Blucher )

An anonymous letter sent to the company, and passed on to the CCC, alleges Ms Burgess "had one of her own inspectors ring up and lodge a complaint to give her the grounds to show up".

The CCC also noted ENCO Precast's claims that Ms Burgess and another WHS official both disclosed confidential company information to the CFMEU in order to "gain a benefit" for the union and to cause detriment to the company.

"Further, you alleged that the officer/s misused their authority and powers to demand names and address of the employees from ENCO Precast, in front of CFMEU members, which did and was intended to threaten, harass and intimidate the employees of ENCO Precast," the CCC wrote.

Mr James, said ENCO has had a good relationship with WHSQ in the past.

"If somebody is overstepping their authority, that needs to be reined in … government authorities shouldn't be assisting unions outside of their authority," Mr James said.

'Let the sun in'

Earlier this year, the Office of Industrial Relations (OIR) ordered an independent investigation into Opposition allegations about the conduct of Helen Burgess.

Queensland Industrial Relations Minister Grace Grace. ( ABC News: Patrick Williams )

The investigation, conducted by Sydney workplace investigations firm O'Connor, Marsden & Associates was completed last month and submitted to the OIR.

That report will now be part of the CCC-ordered investigation.

Ms Burgess told the ABC she does not have the authority to speak to the media about workplace health and safety matters.

Her employer, the OIR, referred the ABC to Queensland Industrial Relations Minister Grace Grace for comment.

Ms Grace said she was aware the CCC had received complaints "regarding the interactions between Workplace Health and Safety and a Brisbane business".

"As is regular practice, the CCC has delegated these complaints to the Office of Industrial Relations for investigation," she said.

Ms Grace said the investigation's findings would be referred back to the CCC and it would be inappropriate to comment further as the matter was ongoing.

Opposition industrial relations spokesman Jarrod Bleijie said the results of the investigation must be made public.

"The best form of disinfectant is to let the sun in," Mr Bleijie said.

"The sunlight needs to go into the whole Office of Industrial Relations and Workplace Health and Safety and the relationship it has with the CFMEU and also Minister Grace's office."