From [1] Reuters:

SYDNEY (Reuters) - Australian authorities believe they have foiled a major terrorist attack, arresting 15 people on Tuesday during raids in the country's two biggest cities of Sydney and Melbourne.

The arrests come less than a week after Prime Minister John Howard said Australia received intelligence about a "terrorist threat."

"We believe ... we've disrupted a large-scale operation which, had it been allowed to go through to fruition, we certainly believe would have been catastrophic," New South Wales Police Commissioner Ken Moroney told Australian television.