Video: Tropical cyclone whips eastern Australia, surfers defy warnings

An "erratic" tropical cyclone lingered off Australia's eastern coast on Thursday, bringing drenching rains and record-breaking waves to a heavily populated region rarely hit by typhoons.

Tropical Cyclone Alfred was 250 kilometres (155 miles) east of busy Brisbane city on Thursday afternoon, but government forecasts warned its slow and "erratic" crawl towards the mainland was growing difficult to predict.

Some four million people were in the firing line along a 400-kilometre (250-mile) stretch of coastline expected to see the worst of the storm.

"We're already seeing gales developing on the coastal fringe," Bureau of Meteorology forecaster Sarah Scully told AFP. 

"There have been very large waves and powerful swells. That's generated by Alfred lingering in the Coral Sea and creating a whole lot of wave energy."