The fire which broke out in a block of flats night reached temperatures of 800°C, it has been revealed.
Andy Earl, of the fire investigation team, said the blaze, which reached temperatures of 800°C, spread into the stairwell because the door of the flat where it started was left open.
He said: "The flat has been 100 per cent damaged by fire but the flat next door, although very close, has little damage. That is because when these buildings are built they are engineered for fire separation. The fire remains in the flat and doesn't spread.
The city council runs a 'Stay Put' policy in most of its flat blocks because fire doors will protect the interior for at least an hour.
Mr Earl added: "Anybody who lives in a block of flats with a Stay Put policy should stick to that policy and stay indoors. The fire in the stairwell reached temperatures of 800C, not capable of sustaining human life, so you are safer indoors.
"Stay inside and let us do our work and get you out."