Norwegian authorities said Friday they had given up hope of finding four Finnish and Swedish cross-country skiers alive after they appeared to have been caught in an avalanche in the Arctic two days ago.

The skiers, three Finnish men and a Swedish woman, were reported missing by a friend on Wednesday around 4:00 pm (1500 GMT) in Tamokdalen in Troms county, northern Norway.

Bad weather in the region has complicated the search, but a helicopter rescue team on Friday detected two transponder signals in the region hit by the avalanche. 

"This confirms our assumption that the missing were swept away by the avalanche," Troms police commissioner Astrid Nilsen told reporters.

"We do not consider it feasible that any of the four could have survived," she said, noting that almost two days had passed since the avalanche.

Doctor Mads Gilbert of the University Hospital of North Norway stressed that the chances of survival in such cases could be counted "in minutes, not hours".

"We are absolutely convinced that there is no medical basis to continue to search for (these people) as if they were still alive," he said.

Norwegian police did not disclose the identities of the four, but said they were all in their thirties.