Firefighters remained at the scene of a large straw stack fire which continued to burn more than 15 hours after the fire service arrived.
Fire crews from Hingham and Attleborough were called to reports of a fire at the former Watton Airfield near Griston at around 4.43pm on Saturday afternoon.
The raging fire and smoke could be seen in the nearby villages as fire crews stayed overnight to keep an eye on the fire while it burned itself out.
Crews brought the fire under control and left the scene at around 7.52am this morning after handing over to the farmer to undertake a watching brief.
A Norfolk Fire and Rescue Service spokesman said police were dealing with the incident as an arson after around 600 tonnes of straw bales were set on fire.
Late on Saturday night on Twitter, the fire service said: 'Have you ever wondered what 600 tonne of burning straw looks like? Arson has kept Attleborough and Hingham busy tonight, they have been working to stop a large fire spreading to structures and livestock. You may see lots of smoke and fire on Watton airfield, it will burn for some time.'
Norfolk police said they were called by the fire service at around 4.46pm and confirmed they are investigating the fire as an arson.
It is the second suspected arson attack at the old RAF Watton site in recent years, with around £20,000 of damage being caused by a huge blaze in April 2016.
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