Support for veto of Tas mine plan: poll

Two out of three Australians support federal environment minister Sussan Ley vetoing a plan to expand a mine in the Tasmanian wilderness, a new poll shows.

A preliminary decision is due by Tuesday on the proposal from Minerals and Metals Group (MMG) - a majority Chinese government-owned company - to build a new tailings dam in the state's northwest Tarkine rainforest.

Ahead of the expected call, progressive think tank the Australia Institute last week surveyed 1001 people to gauge their view on the controversial project.

The survey, released on Sunday, found 65 per cent of respondents either strongly supported or supported Ms Ley stepping in to stop the rainforest clearing and insist MMG use an alternative site.

Less than one in five said they would oppose such a move.

Greens (70 per cent) and Labor (69 per cent) voters were the most likely to back that action, although a majority of coalition (65) and independent-aligned (60) people were still supportive.

NSW, Victoria, Queensland and Western Australia respondents were all broadly supportive of Ms Ley using her powers to quash the proposal.

The views of Tasmanians, whom the project's potential environmental and economic pros and cons directly concern, were not provided due to the state's small sample size.

Former Australian Greens leader Bob Brown, whose foundation has blockaded MMG machinery leading to 15 arrests over the past fortnight, said the poll was instructive.

"It's is must-do for the minister as this is habitat for nationally-listed species vulnerable to extinction including Tasmanian devils, quolls, giant wedge-tailed eagles and owls," he said in a statement on Sunday.

"The campaign to save this rainforest will grow rapidly if minister Ley fails to act."

His group has maintained a constant on-site presence outside Minerals and Metals Group's 85-year-old zinc, copper and lead operation at Rosebery, on the Pieman River, for more than 100 days.

The action has been designed to disrupt woodchip logging in the area as well as hold off MMG road clearing in preparation for the potential tailings dam.

The project would involve piping toxic waste some 3.5km across the Pieman to a proposed 140-hectare reservoir and clearing as much as 285ha of wilderness including rainforest.