The community closest to the proposed Gahcho Kué Diamond Mine is reinforcing its opposition to the project.
In its final remarks for the environmental impact review of the project, the Lutsel k'e Dene First Nation says De Beers has a bad track record of spills at its Snap Lake mine, 220 kilometres northeast of Yellowknife.
It also says the community hasn't seen any real benefits from mining.
Other aboriginal groups, such as the Yellowknives Dene and North Slave Metis Alliance, say the negative impacts of a mine can be mitigated.
Earlier this week, the Lutsel k'e Dene First Nation submitted a confidential traditional knowledge report to the panel.
De Beers' proposed Gahcho Kué mine is located about 280 kilometres northeast of Yellowknife. If approved, the mine could be in operation by 2014.
The site is expected to cover 1,200 hectares.