Fire officers have had to call off an investigation into the cause of a blaze in St Paul's because the building is unsafe.

The property in Wilson Street was so badly damaged in the fire on Sunday that the case has been closed without further investigation.

Avon Fire and Rescue Service said that despite being unable to investigate the cause of the blaze they do not believe it was suspicious.

Firefighters were called to the childhood home of the world's first woman doctor, Elizabeth Blackwell, at 4.30pm and firefighters remained on the scene overnight. They returned on Monday.

At the height of the fire, a turntable ladder was used to tackle the flames from above, along with two 45mm jets and three high-pressure hoses.

Thick smoke and flames billowed from the roof of the building as 25 firefighters on five pumps battled to extinguish the fire.

It was out by about 7pm and, as far as the emergency service was aware, no one was in the building.

The roof of the four-storey building has fallen in as a result of the fire and crashed through the floor below.

Studio rooms at the side of the building were reported to have been severely damaged in the fire.

Avon Fire and Rescue spokeswoman, Stephanie Mounsey, said: "The damage to the building is so severe due to the roof and floors collapsing, that it is not safe to send fire investigators inside.

"We are satisfied that the cause of the fire is not suspicious, although the exact cause is unknown."

She said inquiries were made at the scene at the time of the blaze and with the support of the police the decision had been taken to close the incident.