A woman who plunged 268 metres to her death from the Sydney Tower Eye on Thursday after unclipping her harness is believed to be a 22-year-old from the city's south.

She has not yet been formally identified but is understood to be a Sydney local, police said on Friday.

The attraction was closed throughout the day but the observation platform of the Centrepoint Tower is due to reopen on Saturday morning.

This photo shows the woman's body covered by tarpaulin after workers retrieved it after the tragedy on Thursday afternoon

Staff working at the tower said the building was closed 'until further notice following an incident'. Pictured: The tower and the walkway around it where the skywalks take place

But the Skywalk will remain closed while Merlin Entertainments, the company which runs the Sydney TowerEye Skywalk, assist police with an investigation.

A New South Wales police spokesman said: 'The woman is still yet to be formally identified, however is believed to be a 22-year-old woman from southern Sydney.

'All circumstances leading up to the woman's death will be investigated as a part of the police investigation and report to the Coroner.'

Questions will be asked about how the woman was able to unfasten herself from the safety harness on the Skywalk - an attraction on the outside of the tower in the heart of Sydney's CBD.

At 309 metres, it is the second tallest building in the southern hemisphere and the tallest point in Sydney.

Police and Merlin have not released further details answering why the woman was able to undo her harness.

This image, taken through the glass floor of the walkway on the tower, shows the place (at the bottom of the photo) where the woman landed after she fell

But in a statement on Friday afternoon, Merlin said guests on the Skywalk can loosen the safety belt.  

'However all guests are provided with training and sign a Declaration Form prior to embarking on Skywalk that they cannot tamper with or remove the equipment while taking part in the experience,' Sydney Tower Eye Divisional Director Rob Smith said according to news.com.au.

Mr Smith added: 'The health and safety of our guests and staff is always our primary objective.

'Our thoughts are with the family and friends of the guest as well as the wellbeing of all other guests and our team members.'

Mr Smith said the company would be offering counselling to staff while advising visitors affected by what they saw to seek 'professional help'.

The woman is thought to have taken off her harness and climbed over the railing. Seen here are a group of visitors on a Skywalk tour on a separate occasion 

Merlin said it works to provide 'the highest quality standards, conforming to all regulatory requirements, buildings and best practice in the industry'.

The company assured people it carried out daily safety checks, training for staff, maintenance, preventative control measures which are checked by experts. 

Witnesses claim the woman started the walk on Thursday afternoon in her harness but soon became agitated and removed it after threatening to self harm.

The woman is understood to have then fallen off the platform.

Police were called to a 'self harm incident' about 2.40pm on Thursday and began to retrieve the woman's body from a canopy beneath the tower. 

Meanwhile, paramedics treated witnesses, some who were shaking with shock and one woman who had to be taken away in a wheelchair.  

The woman who plunged to her death from Sydney's Centrepoint Tower today fell right past office workers who saw her face as she plummeted, a witness has told Daily Mail Australia. Pictured: The place where the woman landed

Daily Mail Australia understands Safe Work has not been asked to investigate the circumstances that allowed the woman to take her life, but police are as part of their investigation for the coroner.

The Skywalk is described as a 'breath-taking 45 minute guided tour around the outside of Sydney's highest building.' 

A witness named Chris, who was inside the fourth-floor observation deck at the time, told Daily Mail Australia of the chaotic scenes inside the tower after the woman fell.

He said: 'I was inside when I heard a worker start running and yelling back at his co-workers to 'call downstairs''.

Long walk: The Skywalk tour of the Sydney Tower sees daredevils take a 45-minute tour on a glass-bottomed walkway around the tower while hooked up to safety harnesses

'At first, I thought there was a fire but there were no fire alarms so I really didn't know what was going on.

'I walked over to my friends who seemed pretty grim and asked them what happened. 

'They said they had just seen a woman fall. One of my friends said she saw her falling right in front of her face. I asked if she had a parachute and she said 'no'. 

'We could not see where the woman landed because our view directly downwards was cut off at a certain point. My friend said she had a clear view of the woman's face as he was falling because he was turned towards the sky. 

'She said that she looked to be middle aged.' 

Standing on the platform with the woman at the time were an elderly couple, a young girl, and a few others, Chris said. 

'It seemed like nobody knew the woman. We decided to leave because we were feeling a bit uncomfortable, and as we got off the elevator there were a few police officers.'

A spokesman for Centrepoint Tower, also known as Sydney Tower, said the company was 'working closely with the police on this matter and it is being investigated accordingly. 

'At this stage the Sydney Tower Eye Observation Deck and SKYWALK are closed.' 

Police are preparing a report for the coroner.

If you are in need of support please contact Lifeline Australia on 13 11 14 or BeyondBlue on 1300 224 636.