The Abbott government has quietly reopened a visa loophole that will allow employers to hire an unlimited number of foreign workers under temporary working visas, in a move that unions say will return widespread rorting of the system.
As part of a Coalition bid to remove ''red tape'' from the 457 skilled migrant visa regulations, employers will not be penalised or scrutinised if they hire more foreign staff than they applied for.
Before the loophole was closed in 2013 by the Labor government, companies in the mining, construction or IT industries were hiring hundreds more workers than they had applied for. In one example, an employer was granted approval for 100 visas over three years yet in 18 months had brought in 800 workers on 457 visas.
Unions are appalled by the change, which was made on February 14, saying it undermines Australian job security while reopening a loophole that can easily lead to the exploitation of foreign workers.
''It is reopening a rort for employers,'' said Dave Noonan, national secretary of the Construction, Forestry, Mining and Energy Union. ''Even if the department checks, there is no administrative measure they can take.''
The Australian Workers Union said it will also exploit vulnerable workers.
''It's deeply concerning that in a jobs crisis the government is sneaking through changes that undermine local jobs and conditions,'' AWU assistant national secretary Scott McDine said.
In March last year then prime minister Julia Gillard said the visa scheme was ''out of control''. During an election visit to western Sydney she said she wanted 457s tightened ''to stop foreign workers being put at the front of the queue with Australian workers at the back''.
A discussion paper in 2012 also found there was no restriction to the number of 457 workers a company could nominate once a sponsorship was approved.
That year mining magnate Gina Rinehart famously warned that Australians needed to work harder to compete with Africans who will labour for less than $2 a day.
Yet in June last year the boss of Mrs Rinehart's multibillion-dollar Roy Hill iron ore project, Barry Fitzgerald, backed away from the use of foreign workers on 457 visas, saying he was confident he would find the numbers locally.
Before the cap was introduced in 2013, the numbers of 457 visas were quickly rising. In the financial year of 2009-10 there were 67,980 visas granted. By 2012-13 there were 126,350 visas granted, statistics from the Department of Immigration show.
Unions are also known to be hostile to the visa class because it has allowed non-union foreign labour to replace unionised local workers.
The Assistant Minister for Immigration and Border Protection, Michaelia Cash, defended the move by saying it had removed the ''red tape'' of the visa.
''While the Coalition is a government committed to deregulation and the removal of unnecessary red tape, we are equally committed to ensuring the integrity of the 457 program,'' a spokesman for Ms Cash said.
The changes come as the Coalition reviews 457 visas with what unions argue is a ''stacked'' panel.
''These secretive changes come on the back of the government's announced review which has been stacked to deliver a predetermined outcome that will hurt Australian workers,'' Mr McDine said.
The panel comprises John Azarias of Deloitte Australia, Professor Peter McDonald of Australian National University, Katie Malyon of Ernst and Young and Jenny Lambert of the Australian Chamber of Commerce and Industry.