Clive Palmer's embattled north Queensland nickel refinery has contravened its environmental licence due to elevated ammonia levels in two creeks, tests show.
The Yabulu facility, which is being operated by a skeleton staff after 550 workers were sacked last week, is required to report any excessive chemical levels to the Department of Environment within 10 business days, in accordance with its environmental authority.
Queensland Nickel Sales, which is managing the plant, took samples from Alick and Blind creeks on Tuesday and advised the department on Wednesday excessive ammonia levels were detected.
But no reports of environmental harm associated with the breach had been received, the department said.
Environment Minister Dr Steven Miles said the department would investigate.
"We're not yet in a position to confirm the extent of any contamination or, if it did occur, where from the refinery the contamination may have come," he said.
The government is now awaiting test results after taking its own samples, expected early next week.
"When (the department) has the sampling results and the Queensland Nickel Sales investigation report has been submitted, the department can determine if any compliance and enforcement responses are required," Dr Miles said.
Ammonia is one of the contaminants in the refinery's tailings storage facility, which is unlined and generates seepage, he added.
The seepage is managed through a collection system of trenches and dams.
Mr Palmer has said the operation will not fully open again until the end of July, and even then it would only be up and running if his list of five demands were met.
That included the granting of all government licences.
The Palaszczuk government has accused the businessman-turned-politician of playing games with the workers and not being truthful about massive loans he requested of the government last year.