The Yukon government says "elevated" levels of cyanide have been found in a creek downstream from the Victoria Gold's Eagle gold mine, following a heap leach failure and landslide at the facility.

Streicker said levels in Haggart Creek were 0.04 milligrams per litre, while testing in Dublin Gulch showed 0.001 milligrams per litre. "This level of cyanide in Haggart Creek could affect fish," he said. "Fish toxicity testing is underway."

Testing from the mine site itself showed high levels of cyanide, including 8.58 milligrams per litre at the bottom of the slide, he said.

Kelly Constable, the Yukon government's director of mineral resources, said about four million tonnes of material were released in the slide, about two million of which escaped containment.

Thursday's briefing comes a day after Na-Cho Nyäk Dun First Nation called for a halt to all mining activities on their land.