Giant iceberg spotted south of Australia
Australian glaciologist Neal Young pinpointed the slab, which is some 19 kilometres (12 miles) long and about 1,700 kilometres south of the country, using satellite imagery.
He said he was not aware of such a large iceberg being found in the area since the days when 19th century clipper ships sailed the trade route between Britain and Australia.
"I don't recall any mention of one for a long, long time," Young, of the Australian Antarctic Division and the Antarctic Climate and Ecosystems Cooperative Research Centre, told AFP.
"I'm guessing you would probably have to go back to the times of the clipper ships."
Young said the iceberg measured about 140 square kilometres (54 square miles). Hong Kong island's surface area is about 80 square kilometres.
The glaciologist said the iceberg carved off the Antarctic about 10 years ago and had been slowly floating round the icy continent before taking the unusual route north.
He said the "very, very big" iceberg was originally about 400 square kilometres but then split into two smaller pieces.
"This one has survived in the open ocean for about a year," he said. "In that time it's slowly been coming up to the north and north east in the general direction of Western Australia."
The finding comes after two large icebergs were spotted further east, off Australia's Macquarie Island, followed by more than 100 smaller ice chunks heading towards New Zealand.
Young described the icebergs as uncommon, but said they could become more frequent if sea temperatures rise through global warming.
A long tongue of land that points northwards towards South America, the Antarctic peninsula has been hit by greater warming than almost any other region on Earth.
Scientists say that in the past 50 years, Antarctic temperatures have risen by 2.5 degrees Celsius (4.5 degrees Fahrenheit), around six times the global average.
(c) 2009 AFP