Barry Denholm and Peter Meddens died in August 2012 after an accident on the rig floor.

"This was a tragedy for the two men's families and for everyone involved and our sympathy is with Barry's and Peter's families, friends and colleagues," the company said in a written statement to Energy News.

"We have cooperated fully with the authority investigating this tragic incident and have taken all measures that we can to prevent a similar incident in the future."

It described the men as highly regarded workers.

Stena said it was committed to maintaining safe working practices on its rigs and was constantly striving to ensure it offers a safe work environment.

The company pled guilty in the Victorian Magistrates Court last week to failing to maintain a safe workplace.

It will be sentenced later this week.

The workers were killed by a "machinery failure" as they drilled for gas off the Victorian coastline, about 90km southeast of Warnambool for Origin Energy.

It is believed part of a drill dislodged and struck the men.

Investigations found that senior management on the Stena Clyde failed to apply the Stena management of change principles in failing to carry out a new risk assessment and toolbox talk after altering the original plan of works.

Further, Stena conceded that senior members of the drilling crew failed to ensure that a revised risk assessment had been carried out prior to implementing the new plan.