DP World Australia, one of the country's largest ports operators, said on Tuesday hackers had accessed files containing personal details of employees after a cyber incident early this month forced it to suspend operations for three days.
The breach, spotted on November 10, crippled operations at the company, which manages about 40% of the goods that flow in and out of Australia, affecting its container terminals in Melbourne, Sydney, Brisbane and Western Australia's Fremantle.
"While the investigation has shown that customer data was not affected, some of the impacted data includes the personal information of current and previous employees," the company, part of Dubai's state-owned DP World, said in a statement.
State-sponsored cyber groups and hackers have stepped up their assault on Australia's critical infrastructure, businesses and homes, a government report released recently showed, with one attack happening every six minutes.
DP World did not provide any details about the perpetrators but said its investigation confirmed the incident was confined to its Australian operations and did not impact any other markets where the company operates.
No ransomware was found or deployed within the DP World Australia network, the company said.
After spotting the breach, DP World, one of a handful of stevedore industry players in Australia, disconnected from the internet, significantly impacting freight movements.
The company said it had cleared the backlog of more than 30,000 containers by November 20.
(Reuters - Reporting by Renju Jose in Sydney; Editing by Sonali Paul)