The Australian Greens say plans to expand the Ranger uranium mine should be immediately shelved following the release of Federal Government data showing a sulphate contamination spike up to five times the normal rate in the Magela Creek system.

"It's extremely disappointing that Energy Resources of Australia continues to play down its on-going leakage and contamination problems at the mine," said Greens spokesperson Senator Scott Ludlam.

“We called on ERA to come clean about earlier revelations by the Government Supervising Scientist that water with uranium concentrations 5400 times background and a cocktail of other radionuclides are seeping from beneath the tailings dam at Ranger.

“Clearly the company’s poor environmental management has strained relations with the traditional owners who are now opposed to any expansion of the mine unless ERA steps up effective environmental monitoring and stops the contamination.

“The mine’s track record is atrocious with more than 150 spills, leaks and license breaches since it opened in 1981. I share the concerns of local people who have to live with this mine on their land. The idea that the company should be allowed to build another unlined tailings dam on that lease is now unthinkable," Senator Ludlam said.