Fire crews were called to Halton Lea Farm in the early hours of Tuesday morning, after a blaze broke out at the unoccupied building, between 1am and 1.30am.
A police spokesman said: “The fire caused substantial damage to the farm building.
“Inquiries are ongoing to establish the cause of the fire, which is being treated as arson.”
This was the second fire at Halton Lea Farm in recent weeks, following an earlier incident on March 30.
Police said they were not ruling out the possibility of a link between the two incidents.
Anyone with information is asked to call officers on 101.
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