The fire that damaged two ambulances at the Cromwell Ambulance Station last month was caused by an electrical fault.

The two off-duty ambulances were heavily damaged in a fire at 4.30pm on December 30.

St John Central Otago operations manager David Baillie said, following investigations by Fire and Emergency New Zealand, he could confirm the fire was caused by an ‘‘uncommon electrical fault’’.

The initial police report said the fire was suspicious, raising concerns on social media an arsonist could be targeting emergency services.

St John took the health and safety of patients and ambulance staff very seriously, and regularly conducted maintenance and service checks on all vehicles.

‘‘We would like to reassure the Cromwell community that the main Cromwell ambulance is still fully operational and available to serve the region.

‘‘Other resources and vehicles are also already available and fully operational in the short term.

‘‘There is no impact on our service in the Cromwell community and surrounding areas.’’