A fire in Auckland’s city centre continues to smoulder 48 hours after thousands of people were evacuated from the heart of New Zealand’s largest city.

Hundreds of firefighters have been working in shifts to put out the blaze on the roof of the SkyCity convention centre, with reinforcements called in from towns as far away as Hamilton, two hours to the south, which provided 30 firetrucks.

A fire and emergency spokesperson said the blaze was one of the most complex local crews had ever encountered, and specialist urban search and rescue personnel had been brought in to assist 80 firefighters who worked overnight to contain the fire.

Auckland fire: Apec venue in doubt as SkyCity blaze burns for second day Read more

The basement of the convention centre has been flooded, with potentially 400 cars underwater, according to a leaked image sent to the New Zealand Herald.

The fire had prompted an evacuation of SkyCity Entertainment Group’s entire complex, including hotels, casinos and restaurants, as well as hundreds of people in neighbouring apartments and flats, whose health was at risk from the billowing black smoke clouds.

New Zealand’s state television broadcaster TVNZ was also forced to temporarily abandon its city centre headquarters, and and relocate some staff to its Wellington and Christchurch offices, and broadcast remotely.

Wilson Longhurst (@wilsonlonghurst) Much of the @Breakfaston1 whanau in Wellington due to the fire - TVNZ smoke-logged, we’ll be out for days yet. Other Auckland TVNZers in Christchurch too. Proud of what the @1NewsNZ team is putting out as firefighters continue to work hard next-door. pic.twitter.com/8AyFR4glnk

Fire and emergency said in their latest update: “The fire is smouldering but the wind is causing occasional flare-ups. Firefighters are being rotated and fatigue levels are being closely monitored.”

The convention centre, which is still under construction at a cost of NZ$703m, was slated to be the major venue for the 2021 Apec summit. It is the largest construction project underway in New Zealand.

It has the potential to be a beautiful building, it’s unique. Now the plan has to be to restore it. Jacinda Ardern

The prime minister, Jacinda Ardern, said there was “no question” Apec would go ahead in the city and, while the fire was disappointing, a pragmatic response was needed as to where Apec would be hosted.

“It had come so far, and to now see this major, major setback of course will be a real blow to that workforce. But I know they’ll be as committed as everyone here to see that restored,” the prime minister said on Wednesday. “You can see from the outside, it has the potential to be a beautiful building, it’s unique. Now the plan has to be to restore it.”

Auckland’s recently re-elected mayor, Phil Goff, was praised for his leadership during the turmoil. He said they had been expecting the centre to be finished by around August 2020, and the fire damage meant it could now take more than an extra year to complete.

Phil Goff (@phil_goff) This is what the Convention Centre looks like this morning. Small patches of flame and still some but much diminished smoke. Hopefully in the last stages of extinguishing the fire. pic.twitter.com/w2wqVLREHt

Office workers in central Auckland – including council workers and ministry of justice employees – had been asked to work from home until the fire was out and the smoke – which has been causing minor health issues – had dispersed.

Residents in the city centre described the usually bustling CBD as a ghost town, and RNZ reported homeless people were finding it particularly tough. “Not many people pass by and give you stuff, and Skycity has closed down, so no money, no food,” James, a homeless man, said.

Health warnings have been repeatedly issued for the city centre, with health officials telling residents to shut all windows and turn off airconditioning. Visitors have been told to wear face masks if entering the affected area. Many residents have reported coughing and sore throats from the smoke.

Facebook Twitter Pinterest New Zealand prime minister Jacinda Ardern meets some of the firefighters. Photograph: Jason Oxenham/AP

Support has been made available by the ministry of social development to any businesses forced to close due to the fire and protective cordons set up around the site.

Jay Chauhan’s who owns the Taj Mahal restaurant in central Auckland told RNZ local businesses had been badly affected. “It’s so dead since this happened. It’s affecting all the businesses really badly. You can see across the street pretty much all the businesses have shut down.”

Fletcher Building and SkyCity said the extent of the damage and the next steps would not be known until the fire was extinguished and an investigation could start.