Sydney tower block evacuated after residents 'hear cracks'

Residents have been evacuated from a tower block in Australia after many reported hearing cracking noises.

More than 140 people were forced to leave the 33-storey block in Sydney's Olympic Park on Christmas Eve.

Engineers on site told police that the tower had moved by up to two millimetres, 7 News reported.

Train stations and roads near the building were also closed while fire and rescue services carried out assessments of its structural integrity.

Aerial footage showed firefighters setting up tents around the building and redirecting pedestrians.

The tower was only completed in August and has 392 apartments, a retail area and a childcare centre.

Water and gas services were shut off and the tower was being isolated from the power grid, New South Wales Fire and Rescue Acting Inspector Greg Wright said.

Meriton, the operator of the neighbouring building, said in an email to residents that there was "potential for the tower to collapse."

A resident of the Opal Tower told local media he heard a loud bang as if something in the building had "snapped."

Another resident said there were cracks on the building's 12th and 13th floors.

"I'm concerned, of course," he said. "A few days ago the doors looked different, like they couldn't close properly. And you do feel (movement) sometimes when there's strong wind."