GENEVA (AFP) - Three Italian skiers were killed and one remained in critical condition after they were hit by an avalanche in the Swiss Alps on Saturday, police said, adding that a fifth skier had been slightly injured.

The five Italians had been cross-country skiing when they were swept away by an avalanche around 1.40pm (8.40pm Singapore time) near the Grand Saint-Bernard peak, not far from the Italian border, police said.

All five had been dug out alive, and four had been taken by helicopter to nearby hospitals in serious condition, while a fifth was only slightly injured.

"Unfortunately, we have received word from the hospitals that ... of the four heliported, three have died," Jean-Marie Bornet, a spokesman for regional police in the canton of Valais, told AFP.

"The fourth is undergoing resuscitation, so it's quite serious," he said, adding that police could not yet provide details on the age and gender of the victims.

Bornet said harsh weather conditions, heavy winds and thick fog had complicated the search, forcing rescue helicopters to land further away from the avalanche site.