The New South Wales premier, Gladys Berejiklian, has said her government will “hold everyone to account” over damage to a Sydney apartment complex, as authorities work to determine the root cause of persistent cracking within decade-old building.

Residents of Sydney’s Mascot Towers apartments complex have been left in limbo as engineers try to put an end to the cracking, which forced an evacuation on Friday.

Berejiklian said on Sunday the government wants to “get to the root cause” and find out what has occurred.

“There was some speculation it could have been from things that happened in the near vicinity but we need to find out the cause before we know how to act,” she said.

Asked if the NSW government would help displaced residents in the meantime, the premier said, “We’re getting to the bottom of what happened.”

All 122 units and all but two ground-level shops of the decade-old Mascot Towers in Sydney’s inner south were empty on Saturday and no advice has been given on when residents and businesses would be able to permanently return.

On Sunday, owners and occupiers were told engineers had determined three access zones would be put in place for the next five to seven days.

About half of all units would be partly accessible from Monday, so that residents, escorted by the building manager, could return for a short period of time to collect personal items.

“Thereafter the engineer will advise if further monitoring or alternate and corrective action is required,” an update said.

Concerns had emerged about cracks in the building’s primary support structure and facade masonry, prompting moves to install temporary structural support. Some residents were given about an hour to pack their things and evacuate.

Labor MP for Heffron, Ron Hoenig, said he had been told there was no chance the evacuated complex would collapse.

He also suggested residents might be out of the property for about a week.

Initial investigations are expected to focus on a new apartment block that was recently built next door.

“It’s suspicious that the new building is not even occupied and the building that’s been up for 12 years all of a sudden has substantial cracks,” Hoenig said.

Authorities said on Saturday that there had been “identifiable movements in the basement area”, but no signs of any “immediate structural failures”. The airport rail line and Mascot train station, which sits underneath the complex, had not been impacted.

Renters have been informed their temporary accommodation will not be covered by insurance while owners’ alternate housing may also not be covered. A temporary shelter is in place at the Sydney town hall.

Residents and owners will receive a daily update email and have been told to contact the state’s consumer watchdog if the are facing financial hardship.

“It’s a bit annoying to not really know what is going on and move at short notice but we’ll deal with it,” Mascot Towers tenant Jade told reporters on Saturday.

Another tenant, who is now living nearby with a friend, said he was effectively homeless after being given 75 minutes to leave on Friday night.

“The general thing going through my mind was ‘what can I leave here and just go buy’,” tenant Cameron told AAP on Saturday.

Engineers had been surveying the damage over weeks, but noticed a widening in the cracks on Thursday and Friday.

The evacuation comes months after the Opal Tower debacle and with Sydney having experienced a decade-long apartments boom.

In December, hundreds of residents had to be evacuated from the Opal Tower in Sydney’s Olympic Park after a crack developed in a load-bearing concrete panel and the building shifted 2mm – causing plaster to crack and doors to stick in their frames.

In February, an independent report found that multiple design and construction faults had led to damage at the Opal Tower.

Engineers Australia said the situation was further evidence changes were needed in the building and construction sector.

“The evacuation of Opal Tower was a major wake-up call for NSW to get serious about reform,” spokesman Jonathan Russell said in a statement.

“It is time to finally implement the changes agreed by Council of Australian Governments in response to its inquiry into regulation of the sector.”

In response to the Opal tower crisis, the NSW government announced plans to tighten building regulations and inspections.

The premier said strata building policy was “always a work in progress” and “of course” more needs to be done.

“We need to ensure their rights are protected, whether they’re owners or whether they’re tenants,” she said.

Berejiklian said she anticipated a new NSW Building Commissioner would be named in the “very near future”.

Guardian Australia has contacted Mascot Towers for comment.

Australian Associated Press contributed to this report