OSLO: Some 40,000 Brazilians are bringing a group-action lawsuit against Norwegian aluminium producer Norsk Hydro for what they say is toxic waste pollution the company is causing in northern Brazil.

The lawsuit is brought by a group of communities who live in the lower Amazon region in the Brazilian state of Para, mainly members of Cainquiama - the Amazon Association of Mixed Race, Indigenous and Quilombolas - representing some 11,000 families.

They are seeking compensation for what they say is "the incorrect disposal of toxic waste in the Murucupi River, as well as other effects from the presence of Norsk Hydro installations in the region," their law firm PGMBM, said in a statement.

Hydro has three installations in Para: Paragominas, a bauxite mine; Alunorte, a refinery where the bauxite is transformed into alumina; and Albras, where smelters turn alumina into aluminium.

"Victims have been exposed to toxic residues from the processing of aluminium, which can cause health problems such as increased incidences of cancer, Alzheimer's, skin diseases, stomach problems and diarrhea," PGMBM said.

The lawsuit, which is being filed in the Netherlands, also refers to a 2018 spill that occurred at Alunorte.

In early 2018, Hydro apologised for what it said was a "completely unacceptable" spill of untreated water during severe rains at Alunorte but denied that this had resulted in a contamination of the local environment.

The unlicensed release of water led authorities and courts to demand that Hydro curtail its alumina output from Alunorte, triggering in turn the partial shutdown of Albras, resulting in outages that lasted more than 15 months.

PGMBM said the claimants were not filing the lawsuit in Brazil because they were "frustrated at a lack of progress in the Brazilian legal system".