Australian bushfires have caused unprecedented pollution in Sydney and along the country's east coast, officials said Thursday, with smoke and dust burning residents' eyes and prompting a spike in respiratory complaints.

Hundreds of bushfires have burned out of control since September up and down the eastern seaboard, blanketing cities from Sydney to Brisbane in smoke for weeks on end.

The extent of the crisis was made clear Thursday, with the New South Wales department of environment declaring bushfires and dust had caused "some of the highest air pollution ever seen" in Australia.

The region "has experienced other periods of poor air quality that lasted several weeks, including the 1994 Sydney bushfires and the Black Christmas bushfires of Dec 2001-Jan 2002," a spokeswoman told AFP.

"This event, however, is the longest and the most widespread in our records."

New South Wales Rural Fire Service said more than a dozen fires were burning near Sydney on Thursday, including three that carried an emergency warning.

For three weeks the city has seen almost daily air quality warnings.

Bushfires are common in Australia, but scientists say this year's season has come earlier and with more intensity due to a prolonged drought fuelled by climate change.

New South Wales health officials said more people with asthma were turning up at hospitals, and ambulance call-outs for breathing problems were up 24 percent in the week to December 1.

Meanwhile, tourists and residents took measures to combat the smoke, buying facemasks and staying indoors as much as possible.

On Thursday, Sydney's air quality index registered fine particulate pollution -- small enough to penetrate deep inside the lungs -- at over 160 parts per million, far above levels considered to be safe.

Local newspapers and television have posted advice about how to limit the impact of the smoke -- offering tips on what masks to buy and what activities are safest.

The smoke caused golfers at the Australian Open -- one of the world's oldest national opens -- to complain about conditions.

"It's tough to see your golf ball when you're out there playing, where it finishes. Your eyes do burn," said 2015 champion Matt Jones.

"I've got that cough like you've got something in your lungs, phlegm in your lungs or whatever, but it's not fun," he said. "I hope my kids are inside in the hotel room."