Opal Tower: 51 Units Declared Unsafe After Hundreds Evacuated

More than 300 residents in Sydney's west were evacuated on Monday after reports of 'cracking noises' inside a high-rise building.

Police and fire authorities evacuated hundreds of residents and set up an exclusion zone around areas of Sydney's Olympic Park over fears for the structural integrity of the entire building.

Just after midnight on Tuesday residents of those units that had been declared safe were allowed to return to their homes.

But police said 51 units from the 38-storey building had been declared structurally unsafe, with those residents escorted back to gather their belongings overnight.

It's understood they have made their own arrangements for alternative accommodation.

More than 300 residents from the Opal Tower and two other neighbouring buildings spent Christmas Eve at the nearby showground.

Police outside the building on Monday (10 News First)

“This is a large building and it’s critical the safety of the residents comes first,” NSW Police Force Acting Assistant Commissioner Julie Boon said on Monday night.

Boon said engineers were assessing each affected floor to determine whether it was safe.

“It’s been a particularly frustrating time for residents and we’re very aware they are keen to go home the night before Christmas."

A temporary shelter was established at the nearby Royal Agricultural Society building by NSW welfare and emergency services while residents wait for the ‘all clear’, police said.

NSW Police advised on Monday afternoon that the residents of the Opal Tower at Olympic Park, in Sydney's west, had been evacuated.

"An emergency services operation is underway after concerns were raised for the structural integrity of a 30-storey building at Sydney Olympic Park," police said in a statement.

"Occupants have told police they heard cracking noises throughout the morning."

Exclusion zones were set up around the tower, with roads closed and trains diverted from the nearby railway station. On Tuesday morning road closures had been lifted and some trains in and out of Olympic Park station had resumed.

Featured Image: AAP.