Sydney factory fire 'mostly extinguished'

A huge blaze that gutted a waste recycling centre in Sydney's west is mostly extinguished.

Engineers said it was still unsafe for firefighters to enter the Chullora building on Friday afternoon more than 24 hours after the blaze broke out, a Fire and Rescue NSW spokeswoman told AAP.

The fire continued to burn in isolated pockets but was mostly extinguished, she said.

The 70 by 120-metre complex handles batteries, oil, metals, plastics, cardboard, paint and solvents, and electrical equipment, according to the SUEZ Chullora Resource Recovery Park website.

More than 150 firefighters helped contain the blaze, which sent thick, black plumes of smoke over the city's west on Thursday morning.