Ms O'Neil said a report into Australia's migration and visa system, commissioned late last year, will be released before the federal budget is handed down in May.

The review, led by former Treasury secretary Martin Parkinson, was instituted following large backlogs of visa processing and claims of migrant worker exploitation.

"It does show that there are aspects of our migration system which are broken in fundamental ways," Ms O'Neil told ABC Radio on Tuesday.

"It is a system that is unstrategic, it's complex, it's expensive, it's slow, it's not delivering for Australian citizens or businesses or the migrants who are coming here under it."

A separate report conducted by former Victoria Police commissioner Christine Nixon into exploitation in the immigration system will also be addressed before the budget.

Ms O'Neil said the problem of migrant exploitation was bigger than anticipated.

"The scale is wider than I thought it was going to be, but I think the reporting that was done demonstrates that this problem is significant for the country, and it certainly mandates the government taking action," she said.

"The most widespread exploitation we see in the system is in the exploitation of migrant workers.

"It's a problem in migration systems all over the world, but I would say we're in a particularly acute situation here."

Ms O'Neil said it was critical for the government to act on the issue, following reports of human trafficking and sexual slavery.

Australian Associated Press