The National Offshore Petroleum Safety and Environmental Management Authority said it had commenced an investigation into two fatalities on the Stena Clyde mobile offshore drilling facility yesterday morning.
NOPSEMA said the workers were killed during drilling operations being carried out by Stena Drilling (Australia).
Victorian police confirmed the dead men were a 32-year-old Australian from the Northern Territory and a 60-year-old from Scotland.
Stena Drilling is working for Origin Energy on a six-well drilling campaign in VIC/P43.
The Herald Sun quoted Australian Workers Union state secretary Cesar Melhem saying the deaths were the result of a machinery failure.
"A piece of the machinery bounced back and hit both of them," Melham reportedly said.
"One of them was killed instantly and the other died on the way to the hospital."
"They were trying to fix the drill and the gas released; it wasn't an explosion."