The Palerang Council has vowed to fight plans to use cyanide on a proposed gold mine near Braidwood in southern New South Wales amid fears of contamination.

Fresh doubts have been cast over the safety of Dargues Reef Gold Mine at Majors Creek, after an independent report concluded the project would be significantly riskier if it used cyanide for on-site processing.

The report, by Dr Peter Beck of international professional services firm GHD, was commissioned by Palerang and Eurobodalla Councils to advise on the controversial plan, currently before the New South Wales Planning Assessment Commission (PAC).

Unity Mining, which is proposing the underground gold mine near the township of Majors Creek, won approval in 2011 to proceed with the project — although earlier this year it lodged a modification to allow cyanide processing.

The move sparked vocal opposition from some mine neighbours and downstream agricultural and fishing industries, which feared the environmental consequences of a cyanide spill from a tailings dam.

Earlier this month, a landmark orchard in the nearby Araluen Valley, fearful of toxic runoff, announced it was bulldozing thousands of fruit trees.

The GHD report appears to reinforce their concerns, stating any release of cyanide from the Dargues Reef mine presents a risk to downstream catchments, and points to examples of catastrophic contamination from gold mines elsewhere.

Palerang Mayor Pete Harrison today said the council would fight the mine, even if its fate now rested in the hands of NSW Planning.

"Certainly on the basis of that report, per the resolution that was passed last Thursday night, council doesn't support the modification," he said.

"The consultant felt that there was insufficient information to assess the true impact on the site and on all downstream users.

"We need to understand what it is we're getting ourselves in for, because at the end of the day, if the plant's not there, there's no risk."

Mayor Harrison said residents had turned against the mine proposal.

"There are some people who might appreciate the benefit that might come into the Braidwood and Majors Creek region," he said.

"But I think it's fair to say that the vast majority of the community is not very comfortable at all with having a mine in their backyard."

Report author has not visited site: Unity Mining

The report stated the risks ran from localised animal deaths to mass death of aquatic fauna in river systems.

"Some of these accidents have also resulted in fatalities in communities living near the mine," the report stated.

Unity Mining CEO Andrew Mcllwain standing at the foot of where the entrance to Dargues Reef gold mine in Southern NSW. ( ABC News: Craig Allen )

The report also canvassed the possibility of a deliberate release of cyanide into the water catchment.

"Security is also a risk ... as any theft or deliberate sabotage could result in the release of cyanide," the report read.

"These incidences have been rare but have occurred in recent years."

But Unity Mining chief executive Andrew McIlwain dismissed the report as emotive, and criticised the report author for not even visiting the Majors Creek site.

"There's an enormous amount of emotion," Mr McIlwain said.

"I respect that, but we'd like to think that the New South Wales planning department will do the right thing and review it on its technical merits.

"The report had been generated without Dr Beck actually even having a site visit, and in my normal process of business, that would have been imperative."