An Environment Ministry official had a perceived conflict of interest while working for Rio Tinto Alcan when the mining giant sought a controversial permit for its aluminum smelter in Kitimat, B.C., a Victoria lawyer alleges.

The permit allows the company to increase how much sulphur dioxide it can emit in its expansion of the aluminum smelter.

Victoria-based lawyer Chris Tollefson says provincial environment protection officer Frazer McKenzie was working for both the company and the government when the decision was made about the permit.

Tollefson represents Liz Stannus, a Kitimat school teacher, who appealed a provincial decision in 2013 that allowed Rio Tinto to increase the facility's sulphur dioxide release by 56 per cent.

Tollefson says the province's Environmental Appeal Board should reverse the decision to grant the permit because of a conflict of interest.

"I think people would be worried that Rio Tinto is getting special treatment," he says.

The appeal board has already listened to Tollefson's argument in Victoria and the hearings will resume in Kitimat this week, where another B.C. lawyer Richard Overstall is also fighting to appeal the permit.

"The issue there is that in the minds of a reasonable person, there could well be an apprehension of bias."

However, the B.C. Ministry of Environment denies its employee was also working for the mining giant.

"The individual is employed by government, not the company. Beyond that it would be inappropriate to comment about this particular case because it is presently before the Environmental Appeals Board," the ministry said in an emailed statement.