Around a third of Australia’s foreign workers earn $12 an hour or less - approximately half the casual minimum wage.

The comprehensive study of wage theft and working conditions among international students, backpackers and other temporary migrants found large-scale wage theft was worst in fruit and vegetable-picking and farm work, where 15 per cent of workers earned $5 an hour or less.

The report was based on a survey conducted between September and December 2016, with 4,322 responses from people representing 107 countries.

The analysis found that for every 100 underpaid migrant workers, just three went the fair work ombudsman.

“The study dispelled the misconception that temporary migrants are underpaid because they are unaware of minimum wage rates in Australia,” the report said.

“Though they may not have known their precise entitlements, the overwhelming majority who earned $15 or less knew that the legal minimum wage was higher. However, they perceived that few people on their visa can expect to receive minimum wages under Australian labour law, with at least 86 per cent of believing that many, most or all other people on their visa are paid less than the basic legal minimum wage.

“Four per cent of participants indicated that someone in their workplace had threatened to report them to the immigration department,” the report found.

“This included 92 temporary migrants (3 per cent) who had been threatened by their employer or a manager, which was likely calculated to induce compliance with particular work conditions and/or to deter complaint.”

The report concluded that improving support services and immigration safeguards would be crucial to ensuring Australia remained an attractive destination for international students and backpackers.