Govt tough on worker exploitation: Cash

The federal government insists authorities are doing enough to curb the mistreatment of migrant workers and backpackers.

An ABC Four Corners investigation has revealed exploitation of working holiday visa holders on vegetable and fruit farms, and in chicken factories.

Labor senators have vowed to give the issue further attention in a Senate inquiry already underway into the working visa system.

Assistant Immigration Minister Michaelia Cash says while the allegations were concerning, the majority of employers were doing the right thing.

She confirmed the department was investigating the employment of 417 visa holders by on-hire labour firms.

"We are doing all we can to address the instances where workers' rights are being compromised," she said in a statement on Tuesday.

The Fair Work Ombudsman is helping make foreign workers aware of their rights and has an interpreter service available.

The ombudsman has a special team focused on overseas workers complaints which has handled 6000 requests for assistance and recovered $4 million in outstanding wages and entitlements.

It has started legal action in 50 cases.

The National Farmers' Federation says it is developing a best practice scheme for agricultural employment.