The Australian Greens are calling on Energy Resources of Australia (ERA) to use today's Annual General Meeting to provide a full explanation to shareholders of the extent of water contamination seeping from beneath the tailings dam at the Ranger Uranium Mine in Kakadu National Park, and the future liability for clean up costs.

Environmental regulators for the office of the Supervising Scientist recently admitted that water with uranium concentrations 5400 times background and a cocktail of other radionuclides was leaking from the tailings dam at Ranger.

"It's time ERA revealed the exact nature and magnitude of the leak, the total volume of water that has leaked and some estimates for the cost of site remediation," said Senator Scott Ludlam, Greens spokesperson on nuclear issues.

"We were shocked to find that despite knowing about this leakage for years, the regulators don't seem to know how much is seeping, where it is going, or how highly contaminated it is.

"ERA owes it to their shareholders and local communities to fill that knowledge gap, and also make public the estimated liability.

"Unless we have complete transparency, including how ERA plans to rehabilitate the site, any moves to build another tailings dam in Kakadu cannot be contemplated," Senator Ludlam said.