GENEVA, Jan. 14 (Xinhua) -- The Swiss Federal Institute for Forest, Snow and Landscape Research (WSL) on Monday warned that high avalanche danger will be encountered over a wide area, including the ski resort of Davos, where the annual World Economic Forum meeting is going to start next week.

According to WSL, important Swiss winter tourism areas like Davos, Klosters, Grindelwald, Engelberg and Andermatt was warned of the highest avalanche risk rating of "level 5".

What's more, areas above 1,800 meters were cited as being at very high risk of large or extremely large natural avalanches due to the unstable snow pack.

Swissinfo, the international service of the Swiss Broadcasting Corporation, reported that on Monday, two workers trying to set up explosives for a controlled avalanche in canton Valais were hit by a natural one.

As the result, one died, the other was able to dig himself out, the Swissinfo reported, adding that two skiers in Valais were also swept off piste but were able to free themselves from the snow, and another skier in canton Fribourg was injured after being buried three meters deep.

Earlier this month, two people were killed and one injured in separate avalanches in Swiss ski regions.