Director Alex Hannah saw debris from the roof fall on top of vehicles parked in a car park behind the studio.

He watched nervously as the flames headed towards the Seel Street nightspot.

He said: “Within 10 minutes the place had been gutted. It just went crazy all of a sudden. The flames started coming over towards the bar and got quite close. Had it been a hot, sunny, dry day it could have been a different story altogether.

“Smoke came right through the building.

“We’re just glad the fire didn’t spread.”

Naomi Smith, 22, raised the alarm after seeing smoke while stood at the window of her Duke Street apartment.

She said: The roof was popping and crackling . I was petrified, I thought it was going to explode.”

Bars as far away as Concert Square said the blaze had an impact on trade as customers abandoned their drinks to escape the fumes.

The thickness of the smoke was enough to set off the fire alarms at Lloyds bar The Lime Kiln 100 metres away in Fleet Street.

Customer Chris Browne said: “When we got outside we couldn’t see 50 yards in front of us and I didn’t know where the smoke was coming from. It was so thick, you could barely see a thing.”

A Merseyside Fire and Rescue spokesman said the investigation to determine the cause of the fire was ongoing and nothing had yet been ruled out.