Vandals have put lives at risk in Jamestown by damaging the rockfall protection fences above homes.
Shackles have been stolen from the steel defences above the town – which cost several million pounds – and others have been tampered with.
St Helena Government said: “The removal of these shackles would mean that the fence could have failed in the event of a rockfall, with any rocks passing straight through and hitting the properties below.
“These fences have been provided for public safety, and the actions of one or two irresponsible individuals could easily have been much worse than they were.
“The consequences of their actions could have been severe.”
The damage was discovered in a routine inspection. The fence has now been repaired.
“We would urge anyone with any information about the removal of these shackles to contact the Roads Section urgently,” said a statement.
“Specifically if you have knowledge of any other Rockfall fences that have been tampered with, then please let us know so that they can be inspected and if necessary repaired.”