Detectives are appealing for witnesses or anyone with information following a fire involving a barn in East Lulworth.
Dorset Police received a report from the fire service at 3.20am on Saturday, August 15, regarding the fire involving bales of hay in a barn, which also spread to a nearby unoccupied property.
The fire service extinguished the blaze and enquiries to establish the cause of the fire remain ongoing.
Detective Sergeant Erin Kinghorn, of Dorset County CID, said: "At this time, the cause of the fire remains undetermined."
Previously, a spokesperson for Dorset and Wiltshire Fire and Rescue Service said they believed the fire was started deliberately.
DS Kinghorn added: "Enquiries are ongoing, and we continue to liaise with Dorset and Wiltshire Fire and Rescue Service as part of our investigation into the circumstances surrounding this incident.
"I would urge any witnesses, or anyone with information relating to any individual who may be responsible for this fire, to please make contact with us.
"I would also like to hear from anyone who may have witnesses any suspicious activity in the surrounding area during the early hours of Saturday 15 August, or captured any relevant footage on dashcam, home CCTV, or doorbell cameras."
Dozens of firefighters tackled the blaze as 2,000 bales of hay were set alight in the early hours of the morning.
A spokesperson for the fire service said: “We currently believe the fire to have been started deliberately and investigations are on-going.”
At the height of the incident, crews from Poole, Hamworthy, Swanage, Redhill Park, Westbourne, Dorchester, Wimborne, Maiden Newton, Weymouth, Blandford and Beaminster, as well as small off-road vehicles from Bere Regis and Swanage, water carriers from Poole and Yeovil, and a Unimog from Wareham were in attendance.
Approximately 60 firefighters, who worked to prevent fire spread to the adjacent trees, land and property, were at the scene.
The fire service said it was later scaling back but it is expected to have an attendance for some considerable time.
Wareham fire station asked residents to keeps keep doors and windows closed as a precaution to the amount of smoke in the area.
Anyone with information is asked to contact Dorset Police online or by calling 101, quoting occurrence number 55260126732.
Alternatively, independent charity Crimestoppers can be contacted anonymously online using its website or by calling Freephone 0800 555 111.
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