An extremely rare white humpback whale was Tuesday spotted off the Australian coast as he migrates towards warmer tropical waters to mate. 

The albino is widely believed to be Migaloo, the world's best-known all-white humpback who has built up a loyal following in Australia since first being sighted in 1991.

Migaloo is an Aboriginal word meaning "whitefella".

He was seen and photographed off Byron Bay on Australia's east coast, heading north on his annual migration from Antarctica to warmer waters in Queensland state.

"I cried. I screamed 'You gorgeous whale, thank you for being here for us today'," Alison Reid, who saw Migaloo on a whale watching cruise, told national radio.

"He's amazing. It was just an incredible sight, it was so unreal."

Oskar Peterson, who runs the Australian-based White Whale Research Centre, said a study by Southern Cross University in 2004, which managed to get skin samples from the whale, had shown Migaloo was male. He was now believed to be around 30 years old.

The whale is expected to gradually make his way as far north as Cooktown in the Australian tropics before the return trip to Antarctica later in the year.

Australia's east coast humpback population has been brought back from the brink of extinction following the halting of whaling in the early 1960s.  However, there are believed to be only two or three white humpbacks in the world.