An inquiry has begun into a delay in getting fire crews to the scene of the blaze in the pavilion of Weston-super-Mare's Grand Pier.
Avon Fire Service confirmed an alarm activated at 0135 BST on 28 July, more than five hours before crews were called out at 0645 BST.
The alarm system was linked to a company which alerts pier employees, a fire service spokesman said.
They then check to see if the alarm is genuine before contacting the service.
The brigade said the information "forms part of the ongoing investigation and the cause of the fire remains unknown".
The pavilion was destroyed, but much of the walkway survived and was reopened to the public.
A joint statement by the pier's owner, North Somerset Council and fire brigade called for an end to public speculation on how the fire began.
Owner Kerry Michael said: "I have every confidence in the investigation being carried out jointly between the police, the fire service and insurers and I am sure we will all know exactly what happened in due course.
"Until that time, I urge everyone to avoid speculation as it only causes further distress to those involved."
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