Australia on high alert as tropical cyclone Jasper approaches

A tropical cyclone was building strength as it rolled towards northeastern Australia, with authorities warning "life-threatening" floods could swamp coastal regions for days.

Tropical Cyclone Jasper was expected to make landfall around 6:00 pm local time on Wednesday (0800 GMT), but forecasters said gale-force winds were already pummelling some towns.

Some 8,000 homes are already without power, the Queensland state government said, while police have started closing major roads expected to be hit by flooding.

Meteorologists said Jasper was "strengthening" into a Category Two storm as it churned towards the mainland across the Coral Sea.

It was likely to bring flash flooding and winds of up to 140 kilometres (87 miles) per hour, said forecaster Laura Boekel from the government Bureau of Meteorology.

"We've already started to see the impacts of this cyclone and that will get worse as we move through today," she said.

"The major risk for today is flash flooding."

The tourist cities of Cairns and Port Douglas –– both gateways to the Great Barrier Reef –– are in the path of the storm.

Deputy Premier Steven Miles said some parts of the state were already seeing "cyclonic conditions".

He said "dangerous and life-threatening" floods could linger for "days to come".

Authorities are warning of damage to fences, roofs and other property –– urging residents to tie down loose items before the storm arrives.

Flood watches are in place for rivers across the region and power has preemptively been cut to areas where damage is expected.