The SkyCity boss has expressed concern for the welfare of the person - potentially a teenage apprentice - believed to have left unattended the blowtorch that sparked the devastating fire.
The Herald discovered from a well-placed source the teenager, who was working for a sub-contractor, was called for a smoko break and only remembered when he was away from the roof that he may have forgotten to turn off the gas blowtorch being used to help install waterproof membrane.
The source understood he was returning to the roof to check the blowtorch but by then the fire had started.
"The poor guy is in tatters ... he's completely shattered."
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SkyCity Entertainment Group's chief executive Graeme Stephens said there were surveillance cameras operating in the precinct but he didn't know how the fire started.
He was however concerned about the worker who is alleged to have been involved.
"We have been worried about that person. We don't know who it is. There's certainly no witch hunt from our side. We have a genuine concern for their mental health and wellbeing.
"We're not trying to find them and get them back. We don't know the cause of the fire. We have concern for anyone involved. We're absolutely of that view. We need to get to the cause, obviously."
Meanwhile, road and lane closures remain throughout Auckland central.
Only buses were permitted on Wellesley St between Nelson and Hobson St. Left lanes were open on Hobson St between Victoria and Wellesley St. Meanwhile, left lanes on Nelson St were open, including the cycleway.
MPM Waterproofing Services general manager Andrew Pardington told the Herald on the afternoon of the fire he had a team of up to 12 waterproofers at the convention centre when the blaze broke out.
Pardington refused to confirm or deny the new allegation about how the fire started.
Ten different organisations - including police, insurers and other Government agencies - were investigating the blaze that ripped through the roof of the $700 million building.
Fire and Emergency New Zealand region manager Ron Devlin said the investigation, which included mapping affected areas, was ongoing and it was not yet known how long it would take.
More than 150 firefighters were involved in extinguishing the fire which saw toxic thick black smoke pour from the rooftop for four days.
Guests were moved from SkyCity's hotel The Grand and put up in other accommodation. The casino, restaurants, carpark and Sky Tower were all closed that afternoon, as were other nearby buildings, including the District Court, in following days.
While those buildings had reopened, some of those who have returned to work at the convention centre said there remained a strong smell of smoke and reported experiencing dizziness, headaches, coughing and asthma flareups.
Unite Union organiser for SkyCity, Joe Carolan, told Morning Report he still hadn't seen a report from WorkSafe or from the company itself about the air conditions.
"The workers are complaining about burning eyes, burning throat and with our asthmatic workers: shortness of breath. We've had three people who've reported fainting and people have dizzy spells."
Traffic congestion also remained around the convention centre with several surrounding streets still not fully open today.
ROADS PARTIALLY RE-OPENED:
A section of Wellesley St was open only to buses, and only the left lanes were open on parts of Hobson St and Nelson St. The Nelson St cycleway is also open.
Meanwhile, there are some traffic delays early this morning after a crash just before 8am on State Highway 18, Upper Harbour Highway.
Emergency services are at the scene of what is said to be a serious collision. As a result, the westbound left lane and off-ramp to Squadron Drive have been closed.
"Expect delays in both directions as [Auckland traffic] slows to pass the scene'', an alert on Twitter read.
There are also delays coming from Trig Rd and motorists are being told to allow for extra travel time.
The latest flare-up at the New Zealand International Convention Centre at Sky City occurred about 6pm on Monday, but firefighters were able to scale back their presence at the site.
"There are now two trucks present at the site," Devlin said.
Fletcher Building and SkyCity Entertainment confirmed they have contract works and third party liability insurance in place on the New Zealand International Convention Centre construction site.
A construction expert said it was too early to tell if any party will become liable, as it would depend on the reason for the fire.