The developer of a Sydney high-rise building which had to be evacuated on Christmas Eve says it has been “stunned” by structural defects which have led to some residents being barred from their homes.

Emergency services were called to the Opal Tower at Sydney Olympic Park on Monday after those living in the recently completed building heard and saw cracking in a wall throughout the morning.

Residents of 51 units in the 38-storey building are still unable to return to their homes after the units were deemed unsafe, and it appears unlikely they’ll be declared safe any time soon.

Developer Ecove released a statement on Wednesday defending the Opal Tower as a “high quality building”.

It said the builder, Icon, had full liability on the design and construction.

“Ecove has delivered a project that is well above the industry standard,” Ecove director Bassam Aflak said.

“The important fact is that there is absolutely no danger for the residents. We’re confident this localised issue can be fixed. Most people are now back in their homes.”

It comes as the NSW Government has ordered an urgent review of the structural integrity of all buildings in Olympic Park that were approved under fast-track legislation, The Australian reports.

Questions have been raised over whether planning and construction has been appropriately supervised as development rapidly increases in the area.

A structural engineer from the University of Sydney told the newspaper the damage was unlike any he had seen in Australia.

Ali Hadigheh said it was more in line with developing countries where building codes were lax.

Inside the 'cracking' Opal Tower at Sydney's Olympic Park Inside the 'cracking' Opal Tower at Sydney's Olympic Park

Mr Aflak reassured residents they would be covered under warranty.

“Ecove will help them through that process,” he said.

“We’ve all been stunned by what’s happened, and we’ve been heartened by the way the community has rallied to support the residents, from the emergency service crews and the Salvation Army, to the local businesses, hotels and other people who have worked through Christmas to help us through this time.

“We, like the residents, are anxious that the builder defines the problem and resolves it as soon as possible.”

Residents of the 51 units that are considered unsafe were escorted back to their homes to gather essential belongings on Tuesday.

Delsa Daryaei said her Christ­mas was “messed up” after her level 32 unit was deemed unsafe, forcing her to seek accommodation at a hotel with her mother, Mojgan.

“We spent all of our money just for two nights in a hotel,” Ms Daryaei said.

“It’s Christmas, when everything is expensive. I’ve worked all year to have two weeks off, and now I can’t do anything.”

It was a hectic start to Christmas for the 3000 residents evacuated following the failure of an internal wall.

Many residents heard “cracking” noises at the brand new complex and raised the alarm — and a full evacuation followed as authorities scrambled to discover what was wrong.

Yogi, who was doing washing yesterday afternoon, said he thought the noises were strange.

He told The Australian he heard creaking “like from a horror movie” after he turned his machine off, and was not surprised to hear a fire alarm ring throughout the building shortly after.

It is not yet known how long residents of the affected units will be without their homes.

Fire and Rescue NSW Superintendent Adam Dewberry doesn’t expect those units to be declared safe any time soon.

“It’s not as if it’s going to be tomorrow or the next day because there needs to be an element of work done, now it’s just how quickly that work can be done by the engineers to get in and get a really good thorough assessment,” Supt Dewberry said.

He said authorities weren’t yet aware of how many people were affected.

“The actual number we’re not sure of, because of the time of year, because of the evacuation and people have sorted out their own accommodation and got themselves moved on.”

Kiwi tourist Narissa Knight, 20, was left stranded in her bikini, as she was in the pool when the frantic evacuation began yesterday.

“We couldn’t get anything, I was there in my bikini and no shoes on, nothing,” she told The Daily Telegraph.

“I was walking through the mall and I’m like oh my god, I had my towel around me. It was so embarrassing.”

Other residents have expressed their frustration with the situation.

“Even if it is safe, we’re not going to be sleeping there,” the Senior family told the SMH.

“How can you sleep in there thinking the building might collapse? You wouldn’t be able to rest.”

Umeed Katwal paid $1600 through Airbnb to stay in the building.

“It’s basically ruined my whole Christmas because we came from Canberra to move around Sydney,” he told Channel 9.

“When we came back we were shocked that we weren’t allowed to enter, so then we had to find another place to live around, which is a big hassle when you have kids with you.”

Fire & Rescue NSW Urban Search and Rescue (USAR) officers and specialist engineers worked with the building designers and building managers throughout yesterday and into the night to determine the integrity and safety of the affected floors.