OZ Minerals is downplaying the dangers posed by chemicals that spilled earlier this week when one of its freight trains was derailed due to heavy flooding in the Northern Territory.

In a statement forwarded to the Australian Stock Exchange (ASX), the mining firm confirmed reports that up to 1,200 tonnes of copper concentrates were carried by the transport train when it was hit by disaster Tuesday.

Copper concentrate, experts said, is classified as a hazardous material and its transportation comes with strict guidance imposed by authorities.

It was widely believed that OZ Mineral's chemical cargo were all swept away by flood waters, but the company informed authorities that much of the dangers have been cancelled out as the hazardous materials have been diluted.

"Given the large volume of water flowing through the system it is likely that any concentrate that has been impacted by the water would be highly diluted," OZ Minerals told ASX officials.

Notwithstanding the apparent absence of further threats of chemical contamination, OZ Minerals officials have pledged to clean up whatever residues were left by the accident, the amount of which remains undetermined at this time.

All in all, the freight train was transporting some $8 million worth of concentrates, the bulk of which were copper concentrate, OZ Minerals said, though it added that "exactly how much copper concentrate may have been directly impacted by the derailment," would be hard to determine now.

"From an environmental perspective, in consultation with the relevant authorities, concentrate that is accessible will be cleaned up when the area can be safely accessed," OZ Minerals was quoted by Agence France Presse as saying on its statement.

OZ Minerals' assertions have been somewhat backed by NT environment department chief Jim Grant, who told AFP that the concentrates being transported by the derailed train have been washed away by flood waters.

Grant added that copper concentrate was not highly toxic but direct ingestion or inhalation of the chemical could pose health risks.

He, however, rejected claims by OZ Minerals that the substance may have been diluted, explaining that the soluble had most likely scattered around the area, which eliminated much of the dangers it carried.

"It'll present no danger to livestock or kangaroos or birds, but it may have a smothering effect or toxic effect on animals like invertebrates on the bottom of the stream," Grant reminded.