One of the first acts of the Morrison government was to greenlight a private tourism development with helicopter access in Tasmanian world heritage wilderness against the recommendation of an expert advisory body.

The decision, signed by an environment department assistant secretary on 31 August on behalf of the environment minister, Melissa Price, signalled the luxury camp on remote Halls Island in Lake Malbena was not a threat to matters of national environmental significance and did not need approval under federal laws.

The plan – including a communal building, three accommodation huts, walkways and toilets – is strongly supported by the Tasmanian government. It is at the centre of a debate over the extent to which tourism developments should be allowed in the state’s national parks and the Tasmanian Wilderness World Heritage Area, which makes up about 20% of the island.

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But a leaked letter tabled in Tasmanian parliament by the state Greens leader, Cassy O’Connor, shows the National Parks and Wildlife Advisory Council, a state body appointed to give independent advice to the state and federal governments on protected areas, did not support the camp going ahead.

In advice dated 13 July, the council’s chairman, Malcolm Wells, raised concerns about allowing private commercial use of a world heritage area, a plan to erect permanent structures masquerading as standing camps, the impact of frequent helicopter flights and the potential for conflict with others using the area.

The council said although the project was described as a small standing camp, in reality it would involve several buildings, putting it at odds with the area’s “self-reliant recreation” zoning. It challenged claims by the proponent, Wild Drake, that the site would be “rested” in winter to allow sensitive vegetation in the area to recover.

“This appears to be a pretence at suggesting that the proposed buildings are a ‘standing camp’ that is not accessed all year. However, this is undermined by the next statement that up to five commercial trips (a total of 20 days) may run over this ‘resting’ period,” Wells wrote.

The Wilderness Society Tasmanian campaign manager, Vica Bayley, said it was gobsmacking that Canberra would not fully assess a proposal in a world heritage area when a statutory body had recommended it not go ahead. He said national environment laws were transparently inadequate.

“The evidence that the government has ignored its own experts makes a mockery of commitments to meet world heritage obligations,” Bayley said.

Lawyers and activists are campaigning ahead of the next federal election for the federal Environment Protection and Biodiversity Conservation Act to be strengthened or replaced. Hundreds of Labor branches have passed a motion calling on the opposition leader, Bill Shorten, to commit to tougher laws if elected.

The owner of Wild Drake, Daniel Hackett, said he stood behind about 200 pages of evidence submitted showing the Halls Island camp was a cultural and eco-tourism project that would not damage the environment. “The science speaks for itself,” he said.

He said there would be no more than six tourists onsite at a time. They would mostly be bushwalking, kayaking and learning about the area’s cultural history. He said a helicopter was the way to reach the campsite with the least impact. A helipad would not be needed as it would land on an existing rock formation.

A spokesman for Price said the project was a small tourism development and its approval was backed by Aboriginal Heritage Tasmania and expert heritage advice. He said the department had considered all public submissions, including those by the advisory council, and Wild Drake had committed to strict environmental measures including capturing sewerage and grey water and using flight routes that avoided sensitive areas.

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The Tasmanian premier, Will Hodgman, told parliament views on the camp varied, but it had been subject to a robust and extensive assessment process. He said it was proposed in 2015 after his government called for sustainable development proposals in wilderness areas.

“When you objectively consider the lengthy processes this has been through at a state and commonwealth level in my view that should give Tasmanians confidence that this is one of those projects that will make Tasmania the ecotourism capital of the world that we should be,” the premier said.

Hodgman said a world heritage area management plan released in 2016 allowing helicopters to land and take off had been approved by the commonwealth and the World Heritage Committee.

But documents on the UNESCO website show the committee raised concerns about the government rezoning some areas from “wilderness” to “remote recreation” to allow tourism developments and increased aircraft access. Up to 30 tourism developments have been proposed in Tasmanian nature areas.

Hackett said green groups had said from the time the camp was first proposed they would do everything they could to stop it. “I guess they’re coming through on that promise. I would say they are now engaging in bullying,” he said.

The camp needs final approval under the local government planning scheme and from the Parks and Wildlife Service before it can go ahead. The latter has already given draft support.