(Bloomberg) -- DP World Plc is slowly working through a backlog of more than 20,000 freight containers piled up at Australian ports following a crippling cyberattack, as labor strikes impede a return to normal operations.

DP World, one of the world’s largest port operators, has moved fewer than 5,400 containers in total from Melbourne, Sydney, Brisbane and Fremantle ports since early Monday morning, a spokesman said by phone. That cut the logjam in Australia after Friday’s network hack to about 25,000 containers.

The company is looking at a range of options to get through the stockpile faster, the spokesman said on Tuesday, declining to provide details of any alternatives. Even so, he said it may take weeks for output to get back to normal. 

DP World manages almost 40% of goods flowing in and out of Australia and can usually get through 6,000 containers a day at a single port.

The slow progress reflects the double hit of the weekend’s network shutdown and simultaneous strikes by DP World workers. The protracted fallout shows how even a quickly contained hack can hamstring a company for weeks as it investigates the attack and adds extra layers of network protection.

Maritime Union of Australia members are staging 35 separate strikes at DP World port terminals this week, ranging from one-hour work stoppages to a full-day strike in Sydney on Friday. The union says the actions are planned across the DP World network but rarely coincide. It’s seeking 8% annual pay increases over a two-year period.

The strikes are probably cutting DP World’s capacity in Australia by 10% to 20%, said Adrian Evans, assistant national secretary at the Maritime Union of Australia. Workers are striking because the company refuses to negotiate, he said. Similar action is planned next week.

“The ball is in DP World’s court,” Evans said. “Get back to the table and we can resolve this in a couple of days.”

The DP World spokesman said the union action is exacerbating what’s already a challenging situation for the company. 

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.

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