A RADIOACTIVE leak from a uranium mine inside Kakadu National Park had led to calls from environmental groups demanding the Ranger Mine be shut down.
At 1am on Saturday, a tank on the mine site owned by Energy Resources of Australia, was found to have split and leaked a "slurry" of mud, water, ore and acid.
The Rio Tinto-controlled ERA released a statement saying the mixture was contained and there was no impact to the environment.
The Environment Centre Northern Territory is calling for Ranger to be closed.
"This is a massive system failure at an increasingly dysfunctional mine," said ECNT campaigner Lauren Mellor.
"In the last month, ERA have lost control of mine vehicles and containers and now they have lost control of a large volume of containment."
She said federal and territory regulators needed to take "urgent action" against the mine.
ERA general manager of operations Tim Eckersley said ERA protocols kept the spill contained.
"ERA is focussing on the clean up and recovery, and the protection of the environment and the health and safety of our people remains paramount," he said.
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