March 9 (Reuters) - Hundreds of thousands of people in Australia's Queensland state were without power on Sunday after ex-tropical cyclone Alfred brought damaging winds and heavy rains, sparking flood warnings.

Some 316,540 people were without power in Queensland's southeast where the Gold Coast city was the worst-hit area with more than 112,000 without power due to the storm system, energy distributor Energex said in a statement.

The ex-tropical cyclone reached the Queensland coast on Saturday as a "tropical low" after 16 days as a cyclone, prompting preparations by millions of residents. State capital Brisbane was spared the brunt of the storm's impact, which was also felt in southern neighbour New South Wales state.

Prime Minister Anthony Albanese said on Sunday that the "situation in Queensland and northern New South Wales remains very serious due to flash-flooding and heavy winds".

"Heavy rainfall, damaging wind gusts, and coastal surf impacts are expected to continue over coming days," Albanese said in Canberra, in remarks televised by the Australian Broadcasting Corp.

The nation's Bureau of Meteorology said heavy rainfall that could spark flash flooding was developing on Sunday and could impact Brisbane as well as Queensland regional centres of Ipswich, Sunshine Coast and Gympie, it said.

Damaging winds with gusts of around 90 kph (56 mph) were also possible in the state, the bureau said on its website.

"It is now just a weak low as it continues moving further inland through southeast Queensland bringing lots of rain," bureau meteorologist Dean Narramore said, referring to the ex-cyclone.

Brisbane Airport said on X that it reopened on Sunday, but warned that "ongoing weather may affect the schedule".

On Saturday, one man died in floodwater in northern New South Wales, while two Australian defence force vehicles en route to help residents in the city of Lismore were involved in a road collision that injured several officers, officials said.

(Reporting by Samuel McKeith)

((Samuel.McKeith@thomsonreuters.com;))