Workers near a chemical plant in Sydney's south were evacuated over fears a cooling tower could collapse and cause a "significant fire and explosion".
Emergency crews worked to prevent the tower from falling on a supply of highly-flammable hydrogen gas stored next to the plant on Denison Street, Banksmeadow.
Fire and Rescue NSW said the tanks had been safely moved just before 4pm.
Firefighters were called to the scene about 6:15am this morning and found flames spouting 50 metres above the exhaust stack.
Staff began an emergency shutdown of the plant and conducted a controlled burn to stop the flow of gas within the stack.
But firefighters returned to the site just after 9am when informed the tower could collapse due to "structural integrity issues", Superintendent Adam Dewberry said.
He said there were several hydrogen tanks located next door, which could have exploded if impacted.
"If the tower did collapse on these hydrogen tanks we could be talking about a significant fire and explosion ... in the area."
A failure of a water pipe in the facility is believed to have caused damage to the wooden structure surrounding the cooling tower.
As a precautionary measure, an evacuation order was issued for people and local traffic within 800m of the tower.
NSW Police, NSW Ambulance paramedics and firefighters remained on the scene into the afternoon.
Drones and lasers are being used to monitor any movement on the tower.
Superintendent Dewberry said the situation had been "stable" but progress was moving slowly.
