Some of Australia's biggest mining and infrastructure projects are using workers who have gained skilled migrant visas or permanent residency by misleading the government about their employment status.
A Fairfax Media investigation can reveal that a multinational contractor, Murphy Pipe and Civil, repeatedly misled the Immigration Department to help Irish workers fraudulently obtain visas to work on the Queensland Curtis Liquefied Natural Gas project and West Australia's Sino Iron project.
Leaked files and well-placed sources have revealed evidence of widespread rorting of temporary skilled worker 457 visas and, to a lesser extent, working holiday visas.
But Fairfax Media has confirmed that the Immigration Department has failed to investigate the fraud, despite being contacted by whistleblowers over the past three years.
It is also understood the federal government's yet-to-be released inquiry into the 457 scheme has found it has major weaknesses. In a statutory declaration obtained by Fairfax Media, one of the MPC whistleblowers claims the department failed to follow up information he provided about the firm.
The declaration states the whistleblower identified numerous "unskilled workers holding 457 visas that classed them as project co-ordinators and contract administrators. MPC have sponsored a large amount of unskilled overseas workers under the 457 system knowing quite well they would never be engaged in the position stipulated on their 457 visa."
Four others who worked for the firm corroborated the claims, with one revealing they too sought an investigation from the Immigration Department without success and another saying they quit in disgust.
Confidential company documents also corroborate the allegations of visa fraud. The leaked documents include a description of what the Immigration Department was to be told about the skilled role a 457 applicant was to fill. A second reference names the actual, unskilled job to be given to the worker.
Multiple sources aware of the rorting said it involved senior company staff, migration agents and schemes to help overseas workers obtain permanent residency.
In a statement, MPC said ''it would never intentionally commit a breach of the migration act'' and said that it had relied on external advice when sponsoring its workers. The firm also said it needed more information to respond to the allegations but later turned down repeated offers from Fairfax Media to provide a detailed briefing.