Firefighters were called to Manor House, in Owton Manor Lane at around 6.15pm on Sunday, July 3, following reports of a property blaze.
The ground floor of the building was damaged in the incident, with crews spending around one hour containing the flames.
It was the second blaze reported at the former farmhouse in a week after a fire broke out on Thursday evening, June 30.
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Cleveland Fire Brigade have confirmed the cause of Sunday’s fire is “deliberate” and asked members of the public to come forward if they have any information.
The fire service said in a statement: “We were called on 03/07/2022 at 18.15 to a fire on Owton Manor Lane, Hartlepool.
"Two fire engines from Hartlepool were in attendance. One hose reel and two breathing apparatus used. Further fire damage to ground floor of derelict building. The cause is deliberate. We left the scene at 19.12.
“We will continue to work closely with our local partners and encourage our communities to come forward if they have any information on the perpetrators.
"They can report an incident anonymously by calling Crimestoppers on 0800 555 111 or via their website www.crimestoppers-uk.org/”
Crews spent four hours at Manor House when a fire broke out at the farmhouse just before 6.30pm on Thursday, June 30.
The incident caused severe damage to the roof of the building and an investigation was launched.
Crews were also there on Saturday, June 11, when two jets and a water cannon were used.