Helicopter footage captures firefighters battling blaze on roof of SkyCity's National Convention Centre

The video shows large flames and dark smoke billowing from the site near the Sky Tower as firefighters battle the blaze on the roof of the building.

Dave Woon, Assistant Area Commander for Fire and Emergency NZ Auckland, gave an update on the situation just after 3:30pm.

"The fire is burning on the 7th floor and has spread down to the 6th floor. Firefighters are battling the blaze inside the building and are using breathing apparatuses to combat smoke inhalation.

"It is a large fire involving gas cylinders that started around the roof and guttering area and there is insulation on fire that appears to be straw making it a very challenging fire to extinguish.

"We are not yet on top of the fire but should be able to make progress with resources that have arrived," Mr Woon says.

He says there are no injuries at present and is not sure what caused the fire.

A Fire and Emergency spokesperson says 23 fire trucks are at the scene, including an aerial appliance from Hamilton.

Motorists are being told to avoid the CBD, and members of the public should stay away from the cordons.

SkyCity released a statement on the fire: "Just after 1pm today a fire broke out at the New Zealand International Convention Centre.

"The fire is not yet under control. We can confirm that everyone has been evacuated from the NZICC and there have been no reported injuries.

"We are working closely with Fletcher’s and the Fire Service to gather as much information as possible, we do not know the source of the fire at this stage. We are currently assessing the situation and the damage."