SYDNEY - AUSTRALIAN authorities declared a natural disaster along parts of the country's east coast Saturday as heavy floods cut the main road linking major cities, stranding thousands of people.

Torrential rain soaked the Coffs Harbour region north of Sydney overnight, swamping the arterial Pacific Highway with flash floodwaters that isolated almost 5,000 people, emergency officials said.

About 40 people had to be evacuated from the area hit by the raging floods and New South Wales emergency services minister Steve Whan declared a natural disaster, releasing state funds.

More than 500mm of rain had fallen in the past two days, Mr Whan said, in the fifth major flooding incident to hit the region this year.

Floodwaters were expected to peak at 5m at Coffs Harbour on Saturday afternoon before easing, the State Emergency Service said, describing as 'drastic' the cumulative effect of recent downpours.

'Weather conditions have eased considerably over the last few hours. However, we still have some 4,800 people isolated by floodwaters in a number of north-coast communities,' said SES spokesman Phil Campbell. -- AFP