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Disaster: The Ranger mine in the Northern Territory. Photo: Gundjeihmi Aboriginal Corporation

The federal government has suspended operations at the Ranger uranium mine in the Northern Territory, after a major leak of acid and radioactive slurry at the weekend.

The mine's operator, Energy Resources of Australia, insists there has been no environmental impact from the million-litre spill, but this view is contested by local indigenous people and environment groups.

''I have told ERA today that they cannot resume processing at Ranger until the company demonstrates the integrity of the processing plant to the satisfaction of the regulatory authorities,'' Industry Minister Ian Macfarlane said.

''ERA must also demonstrate that Kakadu National Park and human safety remain protected. I understand the concerns of traditional owners and local residents, and can assure them that governments will continue to ensure the mine operates to the highest standards.''

On Friday, workers detected a hole in leach tank one within the mine's processing area, which has a capacity of about 1.5 million litres.

The next day, the tank split, pouring out a slurry of mud, water, ore and sulphuric acid.

In response to a question in parliament on Monday, Senator Mattias Cormann said he had received assurances that the contamination had not reached Kakadu National Park.

''The spill was contained within the plant area and there is no threat to the surrounding area or to human health outside of the immediate area,'' Senator Cormann said.

The NT Environment Centre said it did not believe ERA when the company said there had been no environmental impacts.

''It's clear there's contaminated water from the burst tank on soil,'' director Stuart Blanch said.

There have been more than 200 safety breaches and incidents over the past 30 years at the site, according to the centre, which says the slurry spill overflowed levee banks designed to contain it and got into the mine's stormwater drain system.

The regional organiser of the Australian Manufacturing Workers Union, Bryan Wilkins, said that during the construction and installation of the leaking tank, in 1993 or 1994, the welding was not properly tested. ''I know it wasn't - I was there,'' he said.

An investigation to determine what caused the tank to give way was being commissioned, ERA chief executive Andrea Sutton said.

AAP