The worst storm in decades has lashed Brisbane, Australia's third-largest city, with wind, rain and hail cutting power lines, flooding streets and injuring a dozen people.

State-owned electricity supplier Energex said up to 90,000 homes had been without power, with trees and hundreds of power lines brought down by winds gusting at 140 kph. By the morning, 68,000 homes remained blacked out.

The storm struck during the Thursday afternoon rush hour, trapping commuters for hours in stalled electric trains.

Television news broadcasts showed high-rise windows smashed, light planes flipped upside down on an airfield and cars almost completely submerged in flooded streets.

Queensland state premier Campbell Newman described the storm as the worst to hit the city of 2.2 million people since 1985. He said 12 people had been injured.

Australian Broadcasting Corporation reported that the convention centre that hosted President Barack Obama and other world leaders at the G-20 summit two weeks ago had suffered hail and water damage.

The army was called in to help emergency crews remove fallen trees.