"Based on the assessment of the scene, all three members of the party are presumed to be deceased", Parks Canada, the country's national parks department, said in a statement Thursday.
They found debris with climbing equipment and noticed signs of multiple avalanches in the area, although the trio's bodies have not been recovered.
All three men are professional mountain athletes and are "highly experienced", according to Parks Canada.
Officials extend condolences to the families, friends and loved ones of the mountaineers.
American climber Jess Roskelley and Austrian climbers David Lama and Hansjörg Auer had been attempting a challenging climb on the east face of Howse Peak.
With files from the Canadian Press.
Parks Canada said the climbers began their ascent on Tuesday and had already climbed various Canadian peaks recently.
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Routen says there are plenty of risks for climbers in areas such as Howse Peak. At 20, he climbed Mt. Everest with his father and became the youngest American to reach the summit.
Roskelley is the son of renowned mountaineer John Roskelley.
The son of a Nepalese mountain guide and an Austrian nurse, Lama had also won numerous climbing competitions in his younger years before devoting himself full-time to mountaineering in 2011.
Hansjörg Auer, from Ötztal, Austria, was the first to climb The Fish route on Italy's Marmolada in the Dolomites without a rope or any protections, according to Climbing. Just last fall, he told the Spokesman-Review he believed he was nearly there, with his sights set on challenging peaks in Alaska and Pakistan.
The outdoor apparel company says it is doing what it can to support the climbers' families and friends.
The elder Roskelley said: "When you're climbing mountains, danger is not too far away".
Poor weather conditions have increased avalanche risks in the mountainous area on the border between Alberta and British Columbia, with the search halted for safety reasons.