Man critical after suspicious house fire

Police are investigating the cause of a house fire that left a man in his 60s with significant burns.

The fire is being treated as suspicious, with police searching for several people believed to have fled the scene.

Emergency services were called to Chelsea Drive, Canley Heights, at around 5.45am on Saturday to find the house already well ablaze.

The man had been pulled from the house and was suffering burns and injuries to his limbs.

He was taken to Royal North Shore Hospital and remains in a critical condition

NSW Police Acting Inspector Dave McInerney said it's possible several people were involved with the fire.

"We have a number of lines of investigation that we're looking at, at this stage," he said.

"If anyone can help us with the investigations we're happy to have them come forward."

Inspector Chris Hughes from Fire and Rescue NSW said investigators were working with sniffer dogs to detect potential sources of accelerant.

"We will deploy the dog, the dog will hopefully indicate in certain areas and that will allow Crime Scene to readily gather evidence in that area and then we can have it tested from there," he said.