The audit, which involves less than 1 per cent of the 200,000 foreign workers in Australia, raises concerns over 40 per cent of 457 visa holders, including evidence that many are no longer working for their nominated employer or are not being paid at the rate at which they were promised.

The report also raises questions about the widespread use of the visa, which the government insists is available only to employers who "cannot find an Australian citizen or permanent resident to do the skilled work" they require.