Three aboriginal groups in the Northwest Territories are urging the federal government not to approve the territory's latest diamond mine as it's currently proposed.

The Gahcho Kue mine, a joint venture between diamond conglomerate De Beers and Mountain Province Diamond Inc., is situated almost 300 kilometres east of Yellowknife and southeast of the existing Snap Lake diamond project.

The project passed its environmental review last month, but the Lutsel K'e Dene, the Yellowknives Dene, and the Tlicho government say the company's plans to reduce impacts on the environment are not good enough.

The lifespands of two of the territory's major diamond mines — Diavik and Ekati — are winding down, and although it's smaller, Gahcho Kue could offset that production drop-off. To get at the diamonds, De Beers and Mountain Province Diamonds propose to drain the southern part of Kennady Lake.

The project's critics say the review does not address their concerns about water quality, caribou, or the future of Kennady Lake after it's drained for mining. They also say there's no clear benefit to people in the area.

They're asking the minister of Aboriginal Affairs and Northern Development to order further review on the project.