The fire, half the size of a football pitch, started at about 3am on Wednesday morning in the car park at Les Platons in St John.
It’s one of a spate of suspected arson attempts police have been dealing with over the last few months.
They are asking people to keep a look out and report any suspicious behaviour to them. Anyone with information is asked to call them on 612612 or Crimestoppers anonymously on 0800555111.