A blaze which badly damaged the Hotel du Vin development in Newcastle is now being treated as arson by police.
Developers Malmaison Group had been in the process of converting the site on City Road into a 42-bed boutique hotel when the fire broke out.
Initially investigators thought that the blaze was accidental. But now it is thought that the fire began on the top floor in one of two rooms that had been completed, causing floors below to collapse.
Detective Inspector Lee Buzzeo, of Newcastle CID, said in a statement: "We are now treating the blaze as a suspected malicious ignition and a criminal offence."
"Fire investigators have concluded there appeared to be no internal reason, like an electrical fault, for the fire to have started.
"They assume there was an external source. As the fire took hold so quickly and floors fell in, forensic analysis of the scene proved difficult. We will now be tracing and talking to all staff and workforce who were on the site on Sunday before the fire started."
The inspector said the workforce would be interviewed as witnesses to provide more information about the site and building.
The new hotel, set to open in May, would have had leisure facilities a rooftop garden and gym. It is now due to open late next year.
By Andrew Smith