SYDNEY (AFP) - A powerful explosion tore through a building in inner-city Sydney on Monday, injuring two men and forcing the evacuation of 1,000 others, Australian officials said.

Police said they were investigating the blast at the Quadrant Building in Ultimo which left a ground floor chicken shop ablaze and damaged some offices and residential apartments.

"It was really scary," one resident told the Australian Broadcasting Corporation. "I was awake and felt something and it was that loud, I jumped on the floor."

Acting Commander of City Central Police, Superintendent Chris Keen, said an injured man was found near a lift with severe burns, while another man suffered smoke inhalation.

New South Wales Fire Brigades said residents in several suburbs away heard the explosion after 1:00 am (1400 GMT Sunday) which authorities fear could have caused structural damage to the building.

"About a thousand residents in residential units above this building have been evacuated as a precaution," Superintendent Ian Krimmer told Macquarie Radio.

Authorities were investigating the cause of the blast.

Police said they were also looking into whether there was a link between the explosion and an armed robbery on the chicken shop hours earlier during which an attendant was assaulted.

Keen said police had seized a car parked nearby for forensic testing. He said the car was linked to the injured man who was found near the lift and that the man was not a resident of the building or a worker at the chicken shop.