(Bloomberg) -- DP World Plc is struggling to work through a backlog of 30,000 shipping containers piled up at ports across Australia as the company resumes operations after a cyberattack.

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Friday’s hack on DP World, one of the world’s largest port operators, triggered a company shutdown at the eastern ports of Melbourne, Sydney and Brisbane and at Fremantle in the west. While operations partially resumed on Monday, the investigation into the attack as well as measures to protect the network could disrupt services for days, DP World said in a statement.

The company expects to shift 5,000 containers out of the four ports on Monday, less than a quarter of the typical daily volume nationwide, a spokesman said. With local strikes also hitting DP World in coming days, it may be next week before normal activity resumes in Australia, the spokesman said.

DP World manages almost 40% of goods flowing in and out of Australia, exposing the country to widespread economic and commercial fallout from an attack on a single entity. The maritime trade giant is the latest victim in a string of high-profile cyberattacks this year. Industrial & Commercial Bank of China Ltd. — the world’s biggest lender by assets — was recently struck by a ransomware attack that blocked some Treasury market trades from clearing.

As more ports automate and move away from paper documentation, hackers pose a growing threat to the region’s shipping networks. Ransomware hackers install malware on victims’ systems, holding them hostage until they receive payment.

With DP World struggling to get back on its feet, Australian Home Affairs and Cyber Security Minister Clare O’Neil said the government plans to force businesses to report any ransom incident, demand or payment. Authorities will also provide a guidebook to help companies prepare and deal with ransom demands, she said.

DP World hasn’t received a ransom demand connected to the latest attack and doesn’t know which organization is responsible, the Australian Financial Review cited a top company official as saying.

In an update to importers and exporters earlier on Monday, the Freight & Trade Alliance industry body said there was still disruption at DP World’s Australian ports. According to the update, DP World was restricting exports at Melbourne. It also warned of “unforeseen service impacts” in Sydney and changes or limits to truck access at Fremantle.