A huge fire at a construction site sent clouds of acrid black smoke billowing over Auckland on Tuesday, forcing large parts of the downtown area to be cordoned off as firefighters battled the blaze.

The fire broke out on the roof of the SkyCity convention centre site shortly after 1:10pm (0010 GMT) and quickly spread, Fire and Emergency NZ said.

Office workers were warned to stay inside and turn off air conditioning as a thick pall of smoke engulfed the centre of New Zealand's largest city
Office workers were warned to stay inside and turn off air conditioning as a thick pall of smoke engulfed the centre of New Zealand's largest city AFP / Greg Bowker

Office workers were warned to stay inside and turn off air conditioning as a thick pall of smoke engulfed the centre of New Zealand's largest city, but there were no reports on injuries.

Unconfirmed reports said the fire was started by a construction worker using a blowtorch on the building, which is one of the venues for the 2021 APEC summit being held in Auckland.