THE federal Environment Minister, Peter Garrett, says he will closely study a proposal to expand the Ranger uranium mine in the world heritage-listed Kakadu National Park.

The mine's owner, Energy Resources of Australia, wants to extract uranium from an additional 10 million tonnes of low-grade ore each year at its plant 250 kilometres south-east of Darwin.

A spokesman for Mr Garrett said ERA's plan would be "rigorously assessed before any decision is made".

The mine has had 150 spills, leaks and licence breaches since it opened in 1981. A Senate hearing was told last month that the mine is leaking 100,000 litres of contaminated water from its tailings dam every day. Tailings are piles of crushed radioactive rock left over after the mining process.

David Paterson, ERA's general manager for business development, said on ABC Radio that a well-established process called "heap leaching" would be used to extract uranium from piles of ore that were previously uneconomic to develop.

"It's well established technology that is used around the world," Mr Paterson told ABC radio.

But Dave Sweeney, a campaigner for the Australian Conservation Foundation, said the plan would exacerbate existing environmental problems at the mine which are affecting Kakadu, one of Australia's top tourist destinations.

"This is not responsible industry practice and will exacerbate the existing pressure and increasingly obvious management deficiencies at Ranger," Mr Sweeney said.

Mr Sweeney said Mr Garrett should insist that ERA prepare a public and peer-reviewed environment impact statement, which includes two rounds of public consultation, before considering any expansion.

The company should be forced to include further plans to tunnel under flood plains as part of the statement, he said.

But given the history of the mine, Mr Sweeney said, the best thing the Federal Government could do would be to order ERA to cease mining, clean up the site and leave Kakadu as soon as possible.

Ranger was scheduled to cease mining last year but now hopes to operate until 2021.

"It is shameless and unacceptable that ERA is now seeking to change the rules and expand," Mr Sweeney said.