Governments should help foreign workers on 457 visas find more work when their employment ends, the UN's special rapporteur believes.
Francois Crepeau's 18-day visit to Australia and Nauru coincides with a political debate about the program, with the federal government announcing its cutting from 90 to 60 days the time workers are allowed to stay once they finish a job.
Asked about the change on Friday, Mr Crepeau said for temporary migrant workers getting fired meant going home and it might be difficult finding more work in two months.
"Returning home with nothing is not an option and the employers know that," he said in Canberra.
Exploitative employers use that as a "pressure point" to make people work longer hours without extra pay, deducting extra expenses from their pay and paying workers late.
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Mr Crepeau called for strict oversight of the program, especially in the construction, hospitality and agriculture sectors.
He welcomed the involvement of the Fair Work Ombudsman but said it needed to be better deployed and funded.
As well, the Human Rights Commission could help.
Employees should be assisted to find another employer, just like other Australians, Mr Crepeau said.
"Sometimes we have to wait a year before we find something suitable.
"Migrants must be given the same type of support."
Reducing the time 457 visa holders can stay in Australia looking for work is just part of a range of changes to the program, cabinet minister Christopher Pyne says.
"It certainly will be enough time for them to find another job if there is one there," he said.
Mr Pyne said Labor increased the period visa-holders could look for more work from 28 days to 90 when it was in office.
"We want to put Australian workers first and there are also jobs where there aren't enough Australian workers ... where we need to bring in foreign workers on short-term visas," he said.
"But we have got to make sure it's tightened up because when Bill Shorten was the minister for employment it spiked by 60,000 in one year."
Labor frontbencher Anthony Albanese accused Mr Pyne of playing politics on the issue.
"That was a time of the mining boom when you had a skills shortage," he insisted.
