A man has found his sister and elderly father dead inside their western Sydney family home and police say they’re treating the case as suspicious.

Homicide detectives and local police are investigating the death of the father and daughter, whose bodies were located on Saturday afternoon.

The man made the discovery after travelling to the Blacktown home concerned for the welfare of his family as they weren’t answering his phone calls.

The father, 77, and his daughter, 43, had “no visible signs of injury, however in the absence of any other information, their deaths are being treated as suspicious,” police said.

A police spokeswoman was unable to provide details about the mother.

No further information was available.