Australia's building and construction codes came under scrutiny Sunday after hundreds of residents were evacuated from a high-rise Sydney apartment block where cracks were discovered.

Some residents said they were left homeless and in tears after they were ordered to leave the 10-story Mascot Towers in a southern Sydney suburb late Friday after cracks were found in the structure's beams.

"At this stage, the engineers need to look at the cracks in those beams while the residents aren't there," Fire and Rescue New South Wales state Assistant Commissioner Roger Mentha said.

The incident at the 10-year-old building followed the Christmas Eve evacuation of residents in the recently completed 38-story Opal Tower in the Sydney Olympic Park after "cracking noises" were heard.

Investigators found there were a number of "design and construction issues" that could have led to the damage that saw the structure move "one to two millimeters."

NSW, Australia's most populous state, said after a public outcry over the scare that it would embark on the "biggest overhaul of building laws" in its history.