The Save Happy Valley Coalition has been protesting at the mine since it was found that a rare population of giant snails inhabits the area.

But last month Solid Energy was granted a wildlife permit to move snails from the Mt Augustus mining blocks at Stockton to a nearby habitat and continue work at the mine.

Solid Energy says the permit expressly provides for construction of rockfall protection barriers, silt fences and other works, which are now being hampered by the environmental protests.

“We will search and move any snails before we start work onsite. As a company we operate within the law,” a spokesperson said.

Solid Energy chief executive Dr Don Elder said the Save Happy Valley Coalition had threatened a contractor at the mine, through a letter, with unfounded legal action in an ongoing effort to stop mining at Stockton.

“Obviously they believe they can undermine our business by targeting people who work with us,” he said.

But the environmental group have remained firm in their fight to stop mining in the area, and said all mining should be halted until it was confirmed the snails had survived and flourished in their new location.

The ridgeline area holds about 5 million tonnes of high-quality coking coal. The coal at Mt Augustus, valued at about $NZ400 million, is needed to blend and raise the specifications of lower quality coal in other parts of the site to meet customer orders.