The Dubai-controlled stevedore, which handles 40 per cent of the nation’s international freight, closed its Sydney, Melbourne, Brisbane and Fremantle port operations after detecting a breach on November 10.

Trucks were left idling at port gates and the transfer of 30,000 containers was delayed, with the backlog still being worked through.

The Maritime Union of Australia is calling on Home Affairs Minister Clare O’Neil to launch an investigation into local managers’ knowledge about the risks of the attack on critical supply chain infrastructure.

The union described the shutdown as “one of the gravest failures of corporate governance in recent memory” and claimed the company did not apply security patches to its IT systems that would have addressed its vulnerability to an attack.

“This cyberattack was not a terrible accident but an appalling failure and the managers responsible should be held accountable,” assistant national secretary Adrian Evans said.

Mr Evans said DP World had left multiple questions unanswered, including whether sensitive information from payroll or HR records were accessed.

“Dubai Ports should focus on explaining to their workforce how the company’s failure to close a well-known cybersecurity gap in their IT system might have exposed their workers’ personal and banking data to cybercriminals,” he said.

“Instead, they continue to attack their own workers with pay cuts, roster changes and the undermining of vital safety measures.”

The company is locked in enterprise agreement negotiations with its workforce, with DP World’s Oceania director previously accusing the union of aggressively pursuing a 27 per cent pay increase while rejecting workplace changes that would ensure more productivity.

DP World has been contacted for comment.