On Friday, five of the owls will be sent from Belgium to Finnish Lapland, while two others rescued by Spanish fishermen are set to follow on Tuesday.

They will be placed in northern wildlife reserves for observation, but not released as their rescue came too late, Veijo Miettinen, a Finnish environmental official, told BBC News Online.

They will instead live in very large cages where they will be able to fly freely.

However, their offspring may one day be released into the wild, Mr Miettinen says.

The owls landed on fishing boats, many days' travel from the coast, ready to die, he says.

The fishermen took them in and fed them, before taking them to animal rescue centres.

Mr Miettinen, of the Finnish Forest Research Institute, has since campaigned to get the snowy owls returned to the Arctic.

The owls' plight was highlighted by a Spanish student in Finland who contacted the Finnish authorities after hearing about the rescued owls during a holiday in Spain.

Rare species

They are not an endangered species as such, but a rare species with only a few thousand left in the world, Mike Everett, a spokesman for the UK's Royal Society for the Protection of Birds, told BBC News Online.

They are thinly distributed over enormous areas over the world's northern parts, predominantly in Canada, Russia, Greenland and Iceland, with a smaller presence in Scandinavia.

In the case of the seven owls, a fluke current may have carried them to the fishing boats in the Atlantic Ocean where they were rescued, Mr Everett says.

They have a nomadic lifestyle as they are heavily dependent on the lemming population for survival, he says.

When lemmings are scarce, snowy owls escape the harsh winters of the Arctic Circle by flying southwards.

"This means they appear in areas when they're not normally seen, searching for food," Ingar Jostein Oeien, a scientist with the Norwegian Ornithological Society, told BBC News Online.

The snowy owl rose to fame after starring as the messenger owl, Hedwig, in the Harry Potter film.