A resident of a Sydney apartment block evacuated over structural concerns says he was left crying in the street and threatened with arrest after trying to re-enter the building to retrieve his pets.

Key points: Emergency services were called to Mascot Towers on Friday night after cracking in the building's beams

Emergency services were called to Mascot Towers on Friday night after cracking in the building's beams Nearby businesses have been told to stay shut today and cracking has appeared in a hairdressing salon wall

Nearby businesses have been told to stay shut today and cracking has appeared in a hairdressing salon wall Less than six months ago 3,000 residents at Sydney's Opal Tower were evacuated after beams collapsed

Residents of Mascot Towers in Sydney's inner-south were forced to find somewhere else to sleep on Friday night when their 10-storey building was evacuated after cracking in its beams.

On Saturday morning, adjoining businesses were told not to open and huge cracks appeared in the wall of a nearby hairdressing salon.

Masa Tatewaki, who has lived in the complex for 10 years, said initially he and his partner were told their apartment was not affected, so they decided to move their car from the building garage which was soon to be closed.

A major crack in the basement of Mascot Towers. ( AAP: Bianca De Marchi )

When they went to re-enter the building they were stopped by police.

"We were told we weren't allowed to go back into our unit … they said, 'If you go back in you will be arrested'," he said.

Mr Tatewaki said he became very distressed as their oven was still on and their two dogs were also inside the unit.

"I was just crying on the street," he said.

When Mr Tatewaki and his partner realised another entry to the building was still open they managed to get inside and pack up a few belongings before leaving.

Mascot Towers, which sits right next to Mascot train station, was built 10 years ago. ( AAP: Bianca De Marchi )

Matthew Harris was one of the first people to move into the building in 2008 and now has nowhere to stay.

"Some people have got friends and family in Sydney they can stay with, I'm not one of those people unfortunately," he said.

"I'm very concerned, I have no idea where I'm going to live for the next days, weeks and months."

He said he was dreading how much the property value might fall and said the "Government has ruined things".

"The system is broken, it needs proper checks and balances for builders."

Residents were offered temporary shelter at the Mascot Town Hall last night. ( AAP: Bianca De Marchi )

'Deterioration has been rapid'

In a letter from building management issued on Friday, residents were told an engineer inspected cracking that had developed in the "transfer slab beams supporting the primary building corner".

"Following the inspection, the engineer raised concerns over the safety for residents in the building," the letter read.

In a notice from the apartment block's strata committee on June 13, residents were warned about the possibility of evacuation and told temporary building props had been installed in the carpark.

Support beams were installed last week in the Mascot Towers car park. ( ABC News: Nicole Chettle )

"This is in response to an ongoing and persistent cracking and structural deformation observed within the primary support structure and the facade masonry," the notice read.

"This deterioration has been rapid, hence expedited propping was deemed a necessary precaution to ensure the safety of the building and its occupants."

Local state member Ron Hoenig believed a newly constructed building next door, which is not yet occupied, may be the culprit.

"It's just suspicious … but they're not sure," he said.

"The authorities need to get to the bottom of it to find out who has to pay. But I don't want it to be the owners of the apartments."

Evacuated residents have not been offered accommodation but a temporary shelter at Mascot Town Hall was offered on Friday night.

NSW Minister for Better Regulation Kevin Anderson has called on the owners of the high-rise to be transparent with its residents throughout the investigation.

"Tell us what is going on, tell the community, tell the residents who lived in that building, and still live in that building, so they can make an informed decision about their future," he said.

The cracked wall in the nearby Hyatt's hairdressing salon. ( ABC News: Nicole Chettle )

Less than six months ago, 3,000 residents of the Opal Tower building in Sydney's Olympic Park were evacuated after the building moved "1 millimetre to 2 millimetres".

A report commissioned by the NSW Government found parts of the tower were constructed using "lower-strength concrete" and that "under-designed" critical support beams had burst under extreme pressure.

Following the Opal Tower debacle, the NSW Government said a building commissioner would be introduced to enforce licencing but that role is yet to be appointed.