Mining company Energy Resources Australia has confirmed it wants to expand operations at the Ranger uranium mine in Kakadu National Park, despite recent concerns over contaminated water seeping into local aquifers.

ERA's David Patterson says the company is seeking approval to use sulphuric acid to extract more uranium oxide from existing stockpiles inside the Ranger mining lease, after the company posted record profits last year.

"Well, I think some of the allegations of the environmental groups are not correct, as we're not affecting the aquifers, and indeed, the Office of the Supervising Scientist has confirmed that in every year of our operation we have had no impact on the surrounding environment."

Energy Resources Australia has had 200 environmental incidents logged against Ranger uranium mine, and it was also the first mining company to be successfully prosecuted in the Northern Territory for environmental breaches.