Huge factory fire sends black smoke billowing over Sydney

Sydney and Blacktown airports are on high alert after a large factory fire in Western Sydney sent intense black smoke across the city.

At least 120 firefighters and 24 trucks are now at the waste-recycling factory and have managed to contain the blaze to the building of origin on Muir Road.

Smoke is now visible across the entire Sydney metropolitan, with social media users sharing photos of the dark plumes from the Northern Beaches.

"We've got a large factory fire, that's all I can say at the moment," Fire and Rescue NSW Superintendent Ian Krimmer told Fairfax Media.

Smoke from the blaze could be seen from the other side of Sydney's CBD. Source: Twitter
Eleven fire crews are battling the blaze. Source: 7 News
Smoke could be seen all the way from north shore. Source: Twitter

The recycling centre handles waste materials including batteries, oil, metals, paint and solvents, electrical equipment and general waste, according to its website.

The roof of the building has collapsed, meaning firefighters are unable to access the inferno.

Six boiling gas cylinders remain at the back of the building which are thought to be capable of exploding at any moment, putting firefighters on the defensive.

Fire and Rescue NSW said on Twitter that all people at the site had been accounted for at the business, which is believed to be SUEZ Chullora Resource Recovery Park.

Huge plumes of black smoke could be seen from the other side of the city.

More to come.