About 200 workers had to be evacuated from Sydney's Barangaroo construction site after the fire that caused chaos to Sydney's city centre reignited.
A small fire started in the basement of one of Australia's largest construction sites about 11am on Friday, although it has since been extinguished.
A building union said there were holes in the emergency evacuation process.
"There are glaring holes ... which haven't been addressed based on what's happened just now," Construction, Forestry, Mining and Energy Union safety officer Michael Preston said.
Sydney's city centre was brought to a standstill last week when a large blaze started on the construction site, which initially threatened to bring down a multi-storey crane, and thousands of workers were evacuated.
The fire caused traffic gridlock and prompted union calls for an urgent city-wide audit of construction safety standards.
Traffic gridlock and huge delays for commuters ensued as the Western Distributor was closed.
Mr Preston said workers had slowly been returning to the site since last week's fire and power was being reconnected.
"No one really knew what was going on - to get off site or to stay on site," he said of Friday's fire.
Fire and Rescue NSW said the reignition of such a fire was a common occurrence.
Site developer Lend Lease said it was put out before firefighters arrived.
"Safety remains our No.1 concern and all employees were safely evacuated," a Lend Lease spokeswoman said.