The three men will also have their pay backdated to the time of the dismissal, Fair Work Australia ordered.

It would total $187,000 minus the severance pay given at the time of the redundancy.

The case for the workers in front of Fair Work Australia was handled by the Construction, Forestry, Mining and Energy Union, which argued that it was unfair to retrench 106 employees in May 2013 at the Boggabri mine while six foreign diesel fitters were retained under 457 visas.

When Downer rehired two months later, after it was deemed production needed to increase, the three men were not rehired when they re-applied for their positions.

In his findings on the matter, FWA commissioner Ian Cambridge referred to the decision of Ulan Coal Mines versus A Honeysett and Ors: “Where an employer decides that, rather than fill a vacancy by redeploying an employee into a suitable job in its own enterprise it will advertise the vacancy and require the employee to compete with other applicants, it might subsequently be found that the resulting dismissal is not a case of genuine redundancy.”

CFMEU district president Peter Jordan reportedly told the ABC the redundancies validated the union's argument that the workers should never have been sacked.

He reportedly said he hoped the decision made Downer reconsider the practice of hiring 457 workers over locals.

“They've made applications on a number of occasions to bring 457 visa workers into Australian mining jobs,” he said.

“There are local workers in and around the Boggabri, Narrabri and Gunnedah area without jobs.

“Downer have got to accept the fact that you've got to look after the local community.”