The upper level of the building was well alight when emergency services arrived, and fire crews were initially worried cars in a valet car park on the lower level had been destroyed.

Police later said the cars in the car park sustained smoke and water damage.

Once the fire was put out, a hydroponic cannabis growing set-up was found in the upper level of the two-storey building.

A NSW Police spokeswoman said there were no reports of injuries and no one was believed to have been inside the building at the time of the fire.

A police spokeswoman said it was unclear how damaged the upper level of the building was at this stage as it had not yet been deemed safe enough for investigators to access properly.