500 evacuated in Sydney high-rise fire

A fire broke out in an airconditioning unit on level 36 of the Australia Square building in Sydney's CBD leading to five floors being evacuated.

Fire crews have put out a blaze in a Sydney office tower after about 500 workers were evacuated. (AAP)

About 500 workers have been evacuated from a high-rise building in the Sydney CBD because of an electrical fire.

The blaze broke out in an air-conditioning unit in a boardroom on level 36 of the Australia Square building on George Street, a NSW Fire & Rescue spokesman said.

Six fire crews rushed to the scene at about 1pm on Wednesday.

Five floors of the striking 47-storey circular building were affected by smoke and workers were evacuated.

The fire has been extinguished.