UPDATE: Lansvale factory fire contained, other buildings saved

More than 100 firefighters have managed to contain a raging inferno at a waste management factory in Sydney's south west.

The fire broke out at Donmar Industries in Day Street, Lansvale just after 3.30pm. 

It burned quickly and intensely, fuelled by wooden pallets and other combustibles at the site.

Scores of workers were evacuated from neighbouring businesses and firefighting reinforcements were called in from across Sydney to focus on property protection.

As a result, the damage was confined to the factory where the blaze started.

Paramedics were at the scene as precaution, but so far, there have been no reports of injuries.

At the peak of the fire, swirls of thick, black smoke blanketed the suburb, seriously reducing visibility.

On the Hume Highway traffic was reduced to a crawl in both directions for several hours.

Firefighters will remain at the scene throughout the night to put out any flare ups.