Building union corruption whistleblowers have been threatened and warned not to co-operate with investigations into alleged criminal activity as the federal government prepares to launch a national police taskforce to examine the construction sector.
Fairfax Media can also reveal that corruption suspects have been meeting to plan their responses to the Abbott government's royal commission into unions, raising concerns evidence has been destroyed and false stories agreed upon in a bid to stymie investigators.
Four prominent construction companies in NSW and Victoria have also launched internal investigations after Fairfax Media recently revealed links between their operations, underworld figures and allegedly corrupt officials in the Construction, Forestry, Mining and Energy Union.
A senior manager from one of the companies who was accused of accepting bribes to rig a tender process resigned within hours of the reports being published earlier this month.
At least two CFMEU corruption whistleblowers have allegedly been targeted with threats and intimidation. One was told that they would face retribution if they supported any inquiries.
Another whistleblower, builder Andrew Zaf - who earlier this month revealed to Fairfax Media and the ABC's 7.30 program his role giving CFMEU officials bribes and inducements during the 1990s and early 2000s - has also been intimidated.
Mr Zaf said that in the past fortnight he had reported to police two incidents he believed were linked to his decision to speak out against building industry corruption.
One incident involved an unknown person allegedly tampering with Mr Zaf's car in an apparent attempt to cause an accident.
Mr Zaf also reported to police an altercation at a Melbourne hotel in which a CFMEU identity slammed a door on Mr Zaf's back and abused him. Mr Zaf said this incident involved no physical harm but was an attempt to intimidate him. Mr Zaf said he was looking forward to telling his story at the royal commission and would aid investigators.
Victorian CFMEU secretary John Setka last month strongly denied a claim by Mr Zaf that he was given free roofing material in the mid-1990s as part of an attempt by Mr Zaf to buy industrial peace.
Fairfax Media on Tuesday revealed online the government's plan for a national police taskforce comprising the Australian Federal Police, the Australian Crime Commission and state police to work with the royal commission.
The taskforce proposal comes as senior figures in the Commonwealth, Victorian and NSW governments remain frustrated by a perceived lack of action by police in investigating long-standing concerns about organised crime and graft in the building sector.
In a move that broadens the commission's reach and ability to investigate union corruption, Attorney-General George Brandis is preparing to sign off on a plan that will attach police agencies to the royal commission led by former High Court judge Dyson Heydon.
A spokesman for Senator Brandis confirmed the government was ready to hand police resources to the commission, but said a formal request for those resources had not yet been received.
The government's move comes amid increasing tensions between building union officials, conservative governments and state police.
A Victorian CFMEU organiser was on Tuesday arrested by police and is expected to be charged on summons with alleged trespass on the state government's Regional Rail Link site in Footscray.
CFMEU national construction secretary Dave Noonan said the organiser was on the site in response to a safety call from a member.
Mr Noonan said the organiser had authorised right of entry and had been on the job several times previously but did not have his papers on him when he arrived on Tuesday.
He said the ''heavy handed'' treatment of the organiser followed the prosecution of 75 workers in Western Australia last week by the federal government for attending a rally in Perth a year ago.
The story Construction union whistleblowers warned not to co-operate with corruption investigators first appeared on The Sydney Morning Herald.