Under the existing contract, Patrick moves approximately 503,000 containers, while the new deal, effective immediately, will see Patrick move an additional 190,000 TEU per year, The Age reported.
"The successful execution of this contract with Maersk Line is a significant achievement for our business and it's a testament to the strength of Patrick's container terminal operations," Asciano chief executive officer John Mullen said.
Announcement of the deal comes as Asciano is due to release the findings of a company-wide review into its operations next month.
Mullen had said in February that he was open to selling poor performing assets, believing Asciano businesses were not achieving an adequate return on capital. That raised questions about possible intentions to sell off its container ports operation.
Austock analyst Andrew Chambers said the contract means Asciano is now less likely to divest its port operations.