Police are investigating the cause of a fire in Kennedy Town on Sunday in which an elderly man's body was found, with firefighters saying the believe the blaze is suspicious.

About 200 people were forced to evacuate the building at Smithfield Terrace on Smithfield after the fire broke out at about 7.30pm on Sunday.

Firefighters deployed a hose and used breathing aparatus and were able to put out the fire within about 40 minutes.

The body of a man, thought to be about 76 years old, was recovered at the scene.