Two forklift trucks toppled into the sea from the Palace Pier earlier today (Monday 4 March).
They went through the railings as a 50ft steel truss was being lowered into position during routine maintenance.
No one was hurt and pier bosses are trying to establish how the accident happened.
They are also waiting for the sea and weather conditions to improve to recover the forklifts.
Pier chief Anne Ackord said: “There was an incident today which resulted in two forklifts trucks falling through the perimeter railings.
“Throughout the year we have a continuous programme of steelwork replacement and the forklifts are used in this process.
“This morning the forklifts were assisting in the positioning of a new 15-metre truss which is lowered in the first instance over the side of the pier.
“This is a process that has been carried out hundreds of times but we are looking into how this incident has occurred.
“Crucially, no one was injured or in any danger of being injured and the recovery plan for the forklifts is already in place.”