SOME employers using the 457 visa program were colluding with migration agents to exploit foreign workers under the scheme, the head of the Australian Council of Trade Unions alleged on Monday.
ACTU national secretary Dave Oliver was in parliament on Monday applying pressure to undecided independent MPs to vote for the Gillard government's proposed crackdown on rorting of the program.
Mr Oliver said it was essential the visa program be tightened to ensure employers advertised jobs locally before trying to source overseas workers to fill vacancies.
But he said the responsibility did not just rest with employers, alleging collusion between some larger firms and migration agents who organised access to foreign workers.
Mr Oliver said some agents were going overseas to recruit foreign workers under unusual contracts before signing them up under Australian arrangements once they arrive.
"We understand some of those being signed up under these arrangements are then made to pay their employers massive interest rates on loans given to them for airfares and visas," he said.
"Some of these migration agents are picking up contract fees in the thousands of dollars by finding these workers.
"Once they pay out their loans, some can then be fired and risk deportation back to their home country if they can't find new work."
Mr Oliver said the union had evidence of such arrangements, but could not supply them at the time.
"These arrangements may not be illegal, but they are taking advantage of poor, vulnerable workers and should be condemned," he said.
He said the entire 457 visa system needed stronger safeguards to ensure foreign workers were not exploited, and to ensure skilled local workers got the first chance as new jobs.
However, Australian Industry Group chief executive Innes Willox said all involved needed to be "extremely wary about drawing broad conclusions" on the number of cases of alleged abuse.
"There are around 110, 000 457 visa holders in Australia and the unions - who incidentally utilise the system themselves to hire some of their own officials - can only come up with a handful of alleged cases," he said in a statement.
"Such cases can easily be handled by the current system which has already been tightened up in recent years," he said.
But as the parliament continues to debate the merits of the crackdown, the proposed changes will not be supported by independent Rob Oakeshott.
It is understood other key crossbenchers may pull their support, with Andrew Wilkie supporting Greens amendments, but still considering his position on the final bill.
Independent Tony Windsor said last week he had not yet decided whether he would support the changes or not.
More amendments were also proposed by Bob Katter, to increase market testing before employing overseas workers, as well as cap annual 457 visa numbers at 6000.
Debate was expected to continue in parliament this week.