Explosives and mining services supplier Orica says the closure of its Kooragang Island facility in Newcastle is costing $4 million in earnings each week.
The Kooragang Island ammonia plant has been closed since August 8, when there was a spill that affected residents nearby.
The facility's ammonium nitrate plant was shut down on November 9 after a separate leak of ammonia vapour.
"The plant closures are impacting earnings before interest and tax by approximately $4 million per week," Orica said in a statement on Friday.
Work is being done to put temporary supply chains in place to reduce disruption to customers' operations, it said.
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Orica has appointed an independent engineer to investigate the cause of the November 9 discharge and the suitability of safety and other systems to prevent any further discharge.
The expert engineer has attended the site and his report is expected shortly, Orica said.
"Orica continues to work closely and co-operatively with relevant regulatory authorities towards meeting their requirements to allow both plants to restart in a safe and environmentally sound manner, but is unable at this stage to say when that will occur," it said.
Orica shares were down 23 cents at $24.96 at 1500 AEDT.
