Firies contain huge Sydney factory blaze

A huge factory blaze is expected to create traffic chaos during the early morning commute in the Sydney suburb of Greenacre.

Firefighters battle the blaze at a Sydney factory Source: Fire and Rescue NSW

Up to 100 firefighters have contained a dangerous factory blaze in Greenacre in Sydney's southwest with motorists advised to steer clear of the area.

The fire broke out in a wrecking yard on Rosedale Avenue at about 3.30am on Friday and spread to a neighbouring factory, sending 20 metres flames into the night sky.

A wall collapse contributed to the dangerous operation for firefighters but no injuries have been reported.

The blaze has been contained and crews are working to extinguish it, duty commander at Fire & Rescue NSW Andrew Ticehurst told AAP.

Police are diverting motorists on Brunker Road and the Hume Highway.