Residents of a high-rise building at Sydney's Olympic Park endured a "frustrating" night after being evacuated from their homes amid a major safety scare.
Opal Tower is one of several new luxury apartment blocks in Sydney's Olympic Park and cost $165 million to build.
Concerns were raised, it says, at around 2.45pm local time over the building, which is located near to Australia Avenue.
A resident stands on her balcony as evacuations began.
"We couldn't get anything, I was there in my bikini and no shoes on, nothing", she told the Daily Telegraph. "It was so embarrassing". It wasn't until about 12:30am on Christmas morning that it was finally declared that the building wasn't going to collapse.
Specialists were due to enter the 10th floor to inspect the crack and assess whether the building was safe, Greg White, a spokesman for New South Wales Fire And Rescue, told reporters.
Meriton, the operator of the neighboring building, said in an email sent out to residents that there was "potential for the tower to collapse".
Residents from Opal Tower and surrounding properties had been taken to an evacuation center and it was not clearly if or when they would be able to return to their homes.
NSW Police said residents of these units had been "escorted back to gather their belongings and have made their own arrangements for accommodation".
Engineers and the building's managers remained at the 34-storey building overnight, declaring that 51 units were structurally unsafe.
"Occupants have told police they heard cracking noises throughout the morning".
But there has been no further movement detected on laser monitors deployed by emergency services.
A number of other buildings in the vicinity have also been evacuated.
Exclusion zones and traffic diversions are in place.
"We spoke to people in the building and they got told to evacuate. they thought it was a fire".
The building was built by Ecove as part of a mixed-use development.
Trains have been diverted away from the building as a result of the operation and buses are being used to transport fans to a nearby BBL cricket match at Spotless Stadium.