(Adds De Beers response)
Dec 6 (Reuters) - An environmental group said on Tuesday it filed a lawsuit against De Beers Canada, accusing the diamond producer of failing to report toxic levels of mercury and methylmercury at its Victor Diamond mine in northern Ontario.
The Wildlands League alleged that De Beers Canada failed to report mercury levels from five of nine surface water monitoring stations for the creeks next to its open pit mine between 2009 and 2016.
This was an offense under the Ontario Water Resources Act, the group said in a statement. It said it had alerted the province of Ontario and De Beers Canada to the failures more than 18 months ago.
The remote fly-in/fly-out Victor mine in the James Bay Lowlands of Ontario is about 90 km (56 miles) west of the Attawapiskat First Nation.
"After months and months of silence from Ontario, we felt we had no choice but to file charges," said Trevor Hesselink, Wildlands League's director of policy and research.
De Beers Canada said in a statement that while it could not comment specifically on the allegations while they were before the courts, the suggestions that its environmental reporting had not been appropriate for seven years was inaccurate.
"Our reporting requirements were expanded to a more robust and comprehensive program when the mine began operations in mid2008," the Calgary-based company said.
The miner also said that mercury was naturally occurring and had been present in the region long before mine construction. Mercury is not used in the mining process, it added.
A spokeswoman for Ontario's environment ministry did not immediately respond to a request for comment.
Methylmercury is created when mercury, a metal that poses health risks, is dissolved in freshwater and seawater.
The Victor mine is set to close in 2018 unless De Beers Canada, a unit of global diamond producer De Beers, proceeds with an expansion.
De Beers is 85 percent owned by miner Anglo American Plc AAL.L .