Flooded rivers forced hundreds of people to flee their homes and a cyclone felled power lines and disrupted uranium mining as monsoonal weather blanketed Australia's eastern and northern coastlines.

Residents living in parts of the east coast of New South Wales state were told to leave their homes as the Tweed River broke its banks, emergency services said. Four other rivers in the region have also flooded. In the Northern Territory, on Australia's northern coast, police ordered residents to stay indoors as Tropical Cyclone Helen moved inland before abating into a low pressure system.

"It's all being caused by lows that formed in monsoonal troughs out at sea and then moved onshore,'' Lori Chappel, a spokeswoman for the Bureau of Meteorology said in a telephone interview from Darwin, the capital of the Northern Territory. "The systems seem to be more intense this time of year.''

As many as 600 people were evacuated from around the banks of the Tweed River, 800 kilometers (500 miles) north of Sydney, and a further 200 may have to be removed from low-lying settlements, according to the New South Wales State Emergency Service. The Richmond River is experiencing its worst flood since 1954 and the Wilson, Bellinger and Boonoo Boonoo rivers are all flooded.

Beaches Closed

"The forecast is for more rain, so there is potential for more evacuations,'' SES spokeswoman Catherine Moyle said in an interview. "There are up to 700 people camped up the Boonoo Boonoo River, attending an alternative lifestyle conference and they've been cut off by the flood.''

All but four of New South Wales' beaches, including those in Sydney, were closed as three-meter (10 feet) waves pounded the coast, said Surf Life Saving spokesman Brett Moore. "It's way too rough, and we're advising people not to take to the water,'' he said.

In the north of the country, gale-force winds up to 62 miles per hour and heavy rain lashed Darwin as well as coastal settlements and islands in the Northern Territory earlier today, the bureau said. Communities between Bhulunbuy and Port Roper remain subject to cyclone warnings, while the coast to Weipa in the neighboring state of Queensland is being monitored as cyclone Helen moves east.

The cyclone was 110 kilometers east of the settlement of Adelaide River and 105 kilometers southwest of Jabiru as of 11 a.m. local time, the bureau said.

Gulf Threat

Coastal towns in the Northern Territory and the Kakadu national park areas will continue to experience squally winds and heavy rains today, Chappel said, adding the storm is headed to the Gulf of Carpentaria, where it may pose a risk to communities in western Queensland as early as tomorrow.

Energy Resources Australia Ltd., producer of more than a 10th of the world's mined uranium, yesterday stopped trucking material out of the mines at its Ranger operation in Kakadu, about 230 kilometers east of Darwin, because of the heavy rain.

Although trucks were still grounded because of the rain, production is not likely to be diminished because ore was still being milled at the site, Energy Resources spokeswoman Libby Beath said.

"We're still producing the same amount as last week,'' she said in an interview from Darwin. "The mine is still operating, we just can't use the trucks.''

The Darwin-based company, a unit of Rio Tinto Group, missed contracted deliveries last year after a flood at Ranger stopped production in February.

Stefano Bertolli, a spokesman for Alcan Inc., the Canadian company whose Gove alumina refinery is in the affected area, did not immediately return calls today.

Emergency services in Darwin began cleaning up fallen trees and branches that littered roads there and brought down power lines. The city's 105,000 residents were allowed to leave their homes after being advised by police to remain inside during the storm, according to the police Web Site. Many areas of the city have lost electricity.