An iceberg twice the size of Manhattan discovered 1,700 kilometres off the coast of Australia has prompted a shipping alert.

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This satellite image shows several icebergs breaking off the Antarctic ice shelf in 2000. The iceberg B17B on the left has been spotted 1,700 kilometres from Australia. ((Australian Antarctic Division/Associated Press))

The country's Bureau of Meteorology issued the alert Friday after the iceberg was seen off the country's southwestern coast.

Glaciologist Neal Young of the Australian Antarctic Division found the iceberg using satellite images. Young described it as 19 kilometres long and eight kilometres wide.

The iceberg is one of several that broke off from ice shelves in Antarctica in 2000.

It is expected to break apart as it moves into warmer waters farther north, but the resulting flotilla of smaller icebergs could pose a hazard to ships.

The Australian Antarctic Division has called the presence of such a large iceberg this far north a once-in-a-lifetime event, but cautioned against attributing it directly to global climate change.

Scientists say that ice shelf calvings such as the one in 2000 happen about once every 30 years.

Last month, New Zealand issued a shipping alert when several icebergs were seen moving toward the country's South Island. They have since moved east out into the Pacific Ocean.

With files from The Associated Press