BBC Correspondent Damian Grammaticus: Conditions have been described as "horrendous"

They were among a party of seven who had been taking part in a winter skills course on nearby Ben Nevis. The group was reported missing at around 2230 GMT on Tuesday.

After a search in which an RAF helicopter was forced back to base by high winds, the four bodies were found on Wednesday morning.

The bodies and the three survivors have been brought down amid high winds and the threat of further avalanches.

Scottish climber Cameron McNeish: "Tremendous luck in absolutely vile conditions"

The rescue operation was hampered further by the inaccessibility of the area where the group was found. A spokesman for the Inverness ambulance service said a ski lift was used to bring the survivors down one at a time.

Aberdeen Mountain Rescue spokesman Alan Crichton said it was fortunate that anyone had survived, saying "I think somebody's been looking after them".

Police spokesman Chas Ross describes the condition of the victims

"The quarry we're speaking about is on the east face of Aonach Mor. The foot of the quarry is 1000m and the cliffs up above it are another 500ft above that.

"It's a fairly arduous trek just to get into it," he said.

The survivors - who are described as hypothermic - have been taken to Belford Hospital, Fort William.

Inspector Chas Ross of the Northern Constabulary said rescuers located the first of the avalanche casualties between 0100 and 0200 GMT on Wednesday morning.

"They found that four persons were dead and that there were three survivors from the party of seven. It had consisted of one instructor and six students," he told BBC News 24.

The students were described as "mature" rather than young pupils.

Mountain rescue spokesman Alan Crichton: "There had been a substantial build-up of new snow"

The party were understood to have come from a Scottish-based organisation, but details have yet to be released.

Up to 35 people were involved in the rescue attempt at one point. Mountain rescue teams from RAF Leeming, Leuchars, Kinloss and Lochaber took part in the search, working in gusts of up to 50mph.