AFP

A very rare humpback whale that's entirely white has been spotted near Australia's Great Barrier Reef.

The whale's thought to be a few weeks old and was spotted by a local man.

He said: "I couldn't believe my eyes, and I just grabbed my camera. Then the white calf approached my boat, seeming to want to check us out."

White whales are rare - the reef's rep says there are only 10-15 among the 10,000-15,000 humpback whales living along Australia's east coast.

And it's even rarer for them to be completely white like this one.