Melbourne: The most powerful cyclone to hit Australia in generations has affected over 170,000 people in flood-ravaged northern Queensland province, uprooting trees, tearing off roofs and cutting electricity.

Cyclone Yasi was the worst cyclone that hit the country since 1918. Over 170,000 residents in the affected region were without power and for many it would take a month to get back electricity, according to latest media reports.

Ergon Energy spokesman John Stock said that early reports indicated damage was worse than experienced during Cyclone Larry in 2006. There have been hundreds of reports of fallen power poles and damaged power lines. Witnesses reported roofs being ripped off, buildings shaking and trees flattened under the power of the winds.

No deaths or serious injuries have been reported. Amid the chaos and devastation of cyclone Yasi, a baby girl was also born at one of the Cairns evacuation centres at 6:09 am (local time). The damage was severe across Tully, Mission Beach and Cardwell. Early reports suggest the communities of Mission Beach, where the category 5 cyclone made landfall about midnight, nearby Tully and Innisfail, 50 km north of ground zero were the worst hit.

The Cyclone Yasi brought 340 mm of rain in some areas with the stretch between Ingham and Mission Beach getting 200-230 mm. Queenslanders were now assessing how destructive Yasi was after a terrifying night.

"It's a great relief this morning to be able to say at this time we have no report of casualties, serious injuries or any fatalities," Queensland Premier Anna Bligh said. She said the picture in the region would become clearer as reports will come from smaller and isolated communities.

Meanwhile, immediate threat to coastal communities from a second storm surge still loomed but was reduced this morning and residents were now being allowed to return back to some affected areas. Flood alerts remained in place in some areas as river levels continue to rise.

Prime Minister Julia Gillard also asked north Queenslanders to not let their guard down in the wake of Cyclone Yasi, saying the storm was still dangerous.

Gillard said people needed to stay alert and listen to the advice of emergency services workers."Surging tides, powerlines that are down, flooding danger and there are some parts of Queensland that are bracing for the cyclone to come across land and to still hit," she said in Canberra.