Police are investigating a second deliberately lit fire at Aldinga Beach.

About 2.50am, Wednesday 31 May, police and CFS were called to Ratcliffe Road after reports of an explosion inside a house and the house on fire.

CFS attended and extinguished the fire. The house was vacant after the occupants had left the property after a suspicious fire on Monday 29 May.

Police suspect the fire was deliberately lit and Crime Scene Investigators will examine the scene again today.

Anyone with any information is asked to contact Crime Stoppers on 1800 333 000 or online at www.crimestopperssa.com.au