Police say they are treating a large fire at the Wesley building in Hartlepool town centre as arson.
Cleveland Police confirmed they believe the huge blaze to the former Methodist church and nightclub on Saturday night was started deliberately.
A spokeswoman for Cleveland Police told the Mail: “I can confirm that we are treating it as arson.”
Meanwhile, The Wesley’s owners say they intend to push ahead with plans to convert it into a hotel.
An investigation was launched on Sunday after police and fire chiefs were able to gain access to the building in Victoria Road.
A structural engineer declared the building safe to enter after an assessment.
Damage to the roof caused it to collapse, but the remainder of the building is not believed to have been badly affected.
The building is owned by Stockton-based development company Jomast which was granted planning permission to convert it into a hotel.
Stuart Monk, Jomast managing director, said following the fire: “Obviously, it was a very serious matter and very nasty incident.
“We are grateful that the fire brigade was able to get there and deal with it.
“It appears to have been started by persons unknown.”
Mr Monk added: “Structural engineers have inspected the building and there is just damage to the roof.
“The structural integrity of the building hasn’t been severely impacted.
“The roof will be replaced and the building restored in accordance with the approved plans.
“The company will be continuing with conversion works to bring the property back to use as a hotel with ancillary facilities on the lower ground floor.”
In 2012 Hartlepool Borough Council granted Jomast listed building consent to carry out alterations and change of use for a 49 bedroom hotel and make the lower ground floor a bar/bistro/restaurant.
Dramatic pictures showed the size of the fire and aftermath to the Wesley which has been empty for a number of years.
Flames were seen rising as high as 20 feet from the roof at the height of the blaze which was reported at 8.30pm on Saturday.
Five appliances from Cleveland Fire Brigade, a command control unit, a welfare base and two hydraulic platforms were drafted in at its height.
No one is reported to have been hurt in the incident.
The Grade II listed building, which dates back to 1872, was formerly used as a church, and later a combined nightclub and gym.
Last year Jomast carried out minor repairs to damage to the doors and windows.