WELLINGTON (REUTERS) - New Zealand fire services on Tuesday (Oct 22) were battling a massive blaze on the roof of a convention centre under construction in the city of Auckland, considered to be the country's biggest current building project.

The fire, which broke out at the SkyCity Convention Centre, is close to the iconic Sky City tower in downtown Auckland.

Videos posted by witnesses on Twitter showed fire and black smoke billowing from the roof of the centre.

"Fire is really building. People can be seen on the roof," Auckland's Mayor Phil Goff said in a tweet.

Some 23 fire trucks from across greater Auckland had responded to the blaze, Fire and Emergency New Zealand said in a statement, after it received multiple calls to report flames.

"There have been no reported injuries," SkyCity said on Twitter, adding that everyone had been evacuated from the convention centre, with Sky Tower and a casino closed until further notice.

Hundreds of people, including construction workers, were evacuated from the vicinity of the fire, media reports said.

Traffic was at a standstill in central Auckland with people asked to avoid the business district and urged to take precautions against inhaling smoke.

Police said in a statement that they are assisting Fire and Emergency NZ with cordons and evacuations of workers in the immediate area.

With a floor area of over 85,000 sq m, the NZ$703 million (S$615 million) SkyCity Convention Centre is considered to be the biggest building project underway in New Zealand.

Owned by New Zealand casino operator SkyCity Entertainment Group, the project has been plagued by delays.

New Zealand's largest builder Fletcher Building is building the centre. Shares of SkyCity were down 4 per cent on the New Zealand bourse.