Morrison government approval for contentious mine expansion works in Tasmanian rainforest has been set aside by a judge who ruled the green light was given in error.
Majority Chinese-owned MMG wants to build a new tailings storage dam at Rosebery on the state's west coast, something it says is needed to ensure its base metals mine can operate beyond 2024.
Federal Court Justice Mark Moshinsky on Thursday ordered approval for design and assessment works, granted by former environment minister Sussan Ley, be set aside.
Justice Moshinsky earlier this week ruled the approval was invalid because Ms Ley didn't properly take into account impacts on the habitat of the endangered Tasmanian masked owl.
The Bob Brown Foundation, which brought legal action against the former federal government, says it is time for the project to be canned altogether.
"This proposed tailings waste dump will cause irreversible harm to the environment," campaign manager Jenny Weber said.
"It must be halted and MMG needs to choose their feasible alternative on their mine site outside (the) takayna/Tarkine (rainforest)."
New Environment Minister Tanya Plibersek has been ordered to make a fresh decision on the works proposal.
"I am aware that Justice Moshinsky has handed down his orders regarding MMG. As I will be the decision maker, I will not be making further comment," Ms Plibersek said.
Justice Moshinsky ordered MMG to remove machinery from the site on Monday at a "walking pace" so it causes as little disruption as possible.
Bob Brown Foundation members have been told to keep their distance from equipment and not obstruct MMG personnel.
MMG's plan to build the dam involves clearing up to 285 hectares and constructing a pipe to move waste across the Pieman River.
The Bob Brown Foundation has spearheaded protests against the expansion and says some 100 activists have been arrested at the site.
Tasmania's Resources Minister Felix Ellis, who assumed the role this week following a cabinet reshuffle, has said the mine is important to the state's future and that he planned to speak with Ms Plibersek.
