An adult white killer whale, otherwise known as white orca, has been spotted for the first time during a research cruise by a group of Russian scientists and students.

The whale, nicknamed Iceberg, was seen off the coast of Kamchatka in eastern Russia, BBC News reported.

Adult white orcas have escaped sightings, but young ones have been seen in the past years. In fact, the death of a young white orca in a Canadian aquarium was widely reported in 1972, BBC noted. The young orca died due to a rare genetic condition.

Iceberg, meanwhile, appeared to be healthy, according to the group's spokesperson.

Erich Hoyt, orca scientist, conservationist and author, told BBC the orca their group has sighted is at least 16 years old.

Mr Hoyt, who is also a senior research fellow with the Whale and Dolphin Conservation Society (WDCS), also observed Iceberg's fin was "somewhat ragged," which means the killer whale could be a bit older than their initial calculation.

"It has the full two-metre-high dorsal fin of a mature male, which means it's at least 16 years old - in fact the fin is somewhat ragged, so it might be a bit older," she said.

"Iceberg seems to be fully socialised; we know that these fish-eating orcas stay with their mothers for life, and as far as we can see he's right behind his mother with presumably his brothers next to him," said Mr Hoyt.