Five people were killed and nine others injured when a small boat collided with a fishing trawler late at night in Australia's Sydney harbour.

The impact threw all 14 people on the smaller boat into the water.

Four women and one man - in their late teens or early 20s - died at the scene. The others were taken to hospital, where one was in a critical condition.

The small boat was overloaded, its owner said, and appeared to have been stolen from its berth.

'Joy-ride'

Police said that the collision happened at 0245 on Thursday (1745 GMT Wednesday).

Conditions at the time of the accident were cold and pitch black, reports the BBC's Nick Bryant from Sydney, and there were scenes of chaos on a nearby wharf as the injured were treated.

The cruiser, which was licensed to carry eight people, belonged to Sydney Ship Repair and Engineering (SSRE) company.

Its managing director, John McPherson, said that it had been stolen from its berth.

"Our boats would only go on the harbour at night-time if we were called out to an emergency for one of our clients' vessels and that certainly didn't occur last night," he told the Australian Broadcasting Corporation.

"It appears that somebody has decided that they were going to take our boat for a joy ride and this horrible event's happened."

All SSRE staff had been accounted for and none appeared to be involved, he said.

Prime Minister Kevin Rudd expressed shock at the news.

"This is every parents' nightmare," he said. "For the parents of those who have lost their lives this is just a terrible, terrible day."

The last fatal crash in the harbour was in March 2007, when three people died after a passenger ferry collided with a pleasure boat.