DOZENS of people in Queensland, New South Wales and Victoria all reported seeing a bright light moving in an erratic way in the sky early this morning, prompting speculation of a UFO.

One witness in Redcliffe in northern Brisbane told The Sunday Mail of a ball of light moving across the sky at about 5.50am today.

"It was a perfect spiral of light," the witness said.

"I realised soon it was not the moon but that it was shooting like a comet from the southern sky and off into the northwest."

Another Brisbane resident said: "There was absolutely no sound in a perfectly clear, darkened sky before dawn."

Police and search and rescue crews confirmed they had received calls from Brisbane, the Gold Coast and Sunshine Coast about the UFO.

The weather bureau said there were no weather conditions which would explain the light. A Defence spokeswoman also said she had no explanation.

In Victoria, a Herald Sun reader identified as Matt said he saw the light after fishing on Port Phillip Bay.

“It was really weird,” he said.

“We tried to take photos with our phones but all you could see was black."

The light was also seen in Sydney, Wollongong and Canberra, reports The Daily Telegraph. A witness told the ABC she saw a light "racing across the sky" about 5.50am. She described the light as "like a lollipop swirl" that came from the west and was headed east out to sea.

"It was unreal," she said.

"There was a cloud in the sky - just this light with a swirl in the middle."

Another caller said:"It was a perfect spiral of light.

"I realised soon it was not the moon but that it was shooting like a comet from the southern sky and off into the northwest.’’

However, astronomer Andrew Jacob, acting curator of the Sydney Observatory, said the UFO was most likely SpaceX's Falcon 9 rocket. The rocket was launched yesterday from Cape Canaveral - Saturday morning in Australia.

"It fits best, a rocket travelling overhead with something venting out of it, fuel venting out of the motor," Dr Jacob told AFP.

"The rocket's probably tumbling or spinning a little which creates a spiral effect, a little like water coming out of a hose when you spin it. That's the best explanation I have so far, probably the most likely one."

He said the timing was right for the SpaceX rocket to have travelled over the Atlantic Ocean, Africa and the Indian Ocean and be in skies over Australia around 6am.