The 170-year-old building is located directly opposite from Crumlin Road Gaol and has laid empty since it ceased to function as a courthouse in 1998.

The listed building was put up for sale by Signature Living last September with planning permission to turn it into a hotel.

The fire began shortly before 3am last night and was brought under control hours later after an operation involving up to 30 firefighters.

A spokesperson for the PSNI said the fire “is being treated as deliberate at this time”.