The rail workers' union are pursuing a claim that Chinese engineers are being exploited in New Zealand.
The union sought their claim be taken straight to the Employment Court for legal reasons, but the Employment Relations Authority (ERA) has ruled it will first deal with the claim.
The Rail and Maritime Transport Union (RMTU) said KiwiRail wasn't complying with good faith and social responsibility, after allowing 40 Chinese workers to carry out work on locomotives brought in from China that were contaminated with asbestos.
The trains were bought from Chinese state-owned CNR Corporation Limited (CNR), and the company sent Chinese workers to remove the asbestos and carry out repairs.
A Labour Inspectorate from Ministry of Business, Innovation and Employment investigated a complaint alleging the Chinese workers were paid $61 per day, well below New Zealand's minimum wage of $14.25 per hour.
The Inspectorate found while the train engineers were working in New Zealand they were still employed by the Chinese company.
The workers and company failed to disclose their pay and working conditions to the Inspectorate because of privacy reasons.
The RMTU wanted the case to go straight to the Employment Court, where it could be decided whether or not foreign workers are subject to New Zealand employment law.
In the ERA's decision, the RMTU said KiwiRail outsourced work that could have been done by union members.
It also argued KiwiRail needed to comply with its obligations of good faith and social responsibility, and desist from "utilising exploited foreign workers, or proceeding in reckless disregard as to whether those workers are exploited".
KiwiRail asserted the Chinese workers were not employed by its company, and therefore the matter was going to be difficult to pursue under the Employment Relations Act.
The matter will be heard in the ERA tribunal, unless RMTU seeks special leave from the Employment Court for the matter to be heard there.