The Australian Greens have called for the phased closure of Ranger uranium mine in Kakadu National Park as a report released today shows the impact of planned expansions has been under-estimated by the mine's operators.

Greens nuclear affairs spokesperson Senator Scott Ludlam said the January suspension of the mine's operations, triggered by near-record rains and originally planned for 12 weeks, had been extended into July but a permanent shut-down was the only measure that could reduce the chance of further environmental damage from the mine.

"Energy Resources of Australia has flagged a 2011 first-half loss of between $30 million and $50 million because of the shut-down caused by heavy rainfall, but heavy rains aren't just a threat to the company's bottom line, they can lead to radioactive material escaping from containment sumps into underlying groundwater," said Senator Ludlam.

"In 2009 a government-appointed scientist confirmed Ranger was leaking 100,000 litres of contaminated water into the ground beneath the park on a daily basis. In total, there have been more than 150 leaks, spills, and license breaches at the mine since it opened in 1981."

Senator Ludlam said "it may be that the most economic option is for the company to bring forward its closure plan and explain how it plans to remediate the site".

"An Australian Conservation Foundation report released today shows ERA has under-estimated the size, complexity, cost and impact of a proposed expansion of operations at Ranger."

"The company's intended use of acid heap leach processing in the high-rainfall Kakadu region poses serious risks to the environment and local Traditional Owners culture of the World Heritage-listed national park."

"The expansion would complicate ERA's closure timeline for the mine, and increase pressure for an extension to the lease. ERA should abandon this plan and close the mine," said Senator Ludlam.