High-ranking sky rail building managers on salaries of about $200,000 allegedly orchestrated a sophisticated copper and wage theft racket that bred a "toxic work culture" on Labor's signature project, a court has heard.

Magistrate Jack Vandersteen has slammed the rackets run from the Andrews government's $1.6 billion Caulfield-to-Dandenong sky rail project, which saw thousands of kilograms of lucrative copper stolen and timesheets allegedly falsified, costing hundreds of thousands of dollars.

It comes as the Victorian Coalition and the Greens call for the case to be investigated by the financial and corruption watchdogs to ensure corruption and theft is not plaguing other major government projects.

"This was a complete rort," Magistrate Vandersteen said as he fined sky rail worker Hozay Crewther, who was convicted in May of stealing copper from the project and selling it for thousands of dollars.

"The entire entire operation in which you [Crewther] were working seemed to be rorting what was otherwise a very good deal: $60 an hour for labouring on top of overtime, on top of any other rates you'd be entitled to."