A migrant worker advocate said New Zealanders should have access to jobs, but they should be quality jobs.

Employers supporting work visa applications to fill low-skilled vacancies must now get sign-off from Work and Income.

Work and Income must confirm no residents or permanent residents are able to do the job.

Union Network of Migrants coordinator Dennis Maga said improving the minimum wage would attract New Zealanders to low-skilled jobs.

He said industries like dairy and aged care don't pay enough to attract local workers, so they employ migrants instead.

"Migrants are actually being employed over locals. I don't think that we're addressing the problems here. We're just making things more difficult."

But he said the changes could be hard on migrants and make New Zealand less appealing for international students.

"At the end of the day, we also have to look after the local workforce. It's a way of balancing the situation right now."