About 4.30am emergency services were called to a house alight in Church Street, Forbes.

Fire and Rescue NSW officers attended and extinguished the flames.

Police spoke to a 41-year-old woman at the scene, who is assisting with inquiries.

A crime scene was established and investigators are treating the fire as suspicious.

Detectives are appealing to anyone who may have witnessed the incident, or who have information about the fire, to contact them.