SYDNEY, Dec 12 — Facing angry street protests and mounting political pressure, Australia’s prime minister today broke a long silence to acknowledge "troubling” bushfire smoke that has engulfed his native Sydney for more than a month.

"I’ve lived all my life, pretty much, in Sydney and the haze that has come from those fires, I know has been deeply troubling to Sydneysiders,” he said, ending weeks of studied silence.

Yesterday up to 20,000 people — many wearing face masks — marched in Sydney, demanding Prime Minister Scott Morrison address directly the crisis that has caused health problems to spike and forced residents indoors.

Hours later the conservative leader insisted he understood the concerns of greater Sydney’s five million residents, who have been coughing and spluttering through thick smoke off-and-on since October.

"I know how unusual it is to see that haze across my city. And I know how distressing that has been, particularly for young people, who wouldn’t have seen that before,” he said.

He also made a rare admission that climate change is one of the "factors” causing unprecedented bushfires that have destroyed millions of hectares of land, more than 700 homes and caused toxic smoke to bathe Australia’s largest city.

"The dryness of the bush is the biggest factor,” he said noting a long drought in some areas. "And we all know climate change, along with many other factors, contributes to what is occurring today.”

Until now Morrison’s public comments have focused almost exclusively on solidarity with sparsely populated rural communities hit by the fires directly.

A recent poll by Essential Research showed Morrison’s disapproval rating had risen from 36 per cent in September — when the bushfire crisis began in earnest — to 43 per cent today.

Climate is a vexed political issue for Morrison’s Liberal party.

While he once jokingly paraded on the floor of parliament with a lump of coal to show it was not harmful, former leader Malcolm Turnbull broke ranks to demand the party embrace renewable energy and show more leadership.

Any move to significantly reduce Australia’s carbon emissions or curb coal exports could damage Morrison in conservative-voting mining communities, split his party and risk tipping a fragile economy into crisis.

Australia’s lucrative mining industry accounted for more than 70 per cent of exports and was worth a record A$264 billion in the last financial year. — AFP