A team of Russian scientists have reported what they believe is the first-ever sighting of an all-white, adult killer whale in the wild.

The discovery of the six-foot, pure white fin was made by scientists during a research cruise off the eastern coast of Russia, near the Kamchatka Peninsula and the Commander Islands in the North Pacific.

"It is a breathtakingly beautiful animal," Eric Hoyt, one of the scientists, told the AFP.

Hoyt leads the Far East Russia Orca Project, the group that made the discovery and has been following orca whales in the area, protected as Russia's largest Marine reserve, for the past 12 years. The group says it has sighted and catalogued about 1,500 whales so far, but the discovery of the adult male, which they have nicknamed Iceberg, stands out.

"This is the first time we have ever seen an all-white, mature male orca," Hoyt said.

The orca appears to be healthy and interacting normally with the other nearly one dozen whales in its pod, according to Hoyt.

"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," he told the BBC.

The researchers believe Iceberg is at least 16 years old given the "somewhat ragged" nature of his fin. Orca males can live up to the age of 50 or 60 years, although most only live for around 30 years.

"We've seen another two white orcas in Russia but they've been young," Hoyt said.

Hoyt's research team plans to track Iceberg and his pod over the summer months to definitively establish whether Iceberg is albino, a genetic condition that leaves animals unable to produce melanin, a darker pigment.

The team hopes to be able to confirm Iceberg's condition by photographing his eyes instead of the more complex task of taking a biopsy from the mammal.

"If we can get a full close-up of the eyes and they are pink, it would confirm Iceberg is an albino, but we don't know much about albinism in orcas," Hoyt said.

In 1972, a two-year-old white orca named Chimo died while in captivity in Canada from a genetic condition that was believed to have caused its albinism.

More recent sightings of the elusive, albino version of the animal have included a reported sighting off the Aleutian Islands near Alaska in 2008 and interest in a humpback whale nicknamed Migaloo in Australia, although that animal is not believed to be naturally white, the BBC reports.