Local officials said on Monday they had evacuated two dozen residents from vulnerable areas while crews used explosives to reduce dangerous buildups on some slopes above the town.

"When Trump comes on Friday, it is far from obvious whether he will be able to use a fleet of large helicopters to land in Davos," said a source close to the organizing committee. "Large helicopters increase the risk of avalanches."

Landslides and heavy snowfall across the Alps also prompted the closure of several rail and road links, including a highway leading to Switzerland's Gotthard tunnel toward Italy.

Public broadcaster SRF reported that the A2 highway near Gurtnellen was hit by an avalanche and would remain closed in both directions until at least midday on Tuesday.

The Swiss ski resorts of Zermatt, Andermatt and Saas-Fee are cut off from the outside world due to the risk of avalanches.

Reuters - Xinhua - AP