Thieves have tunnelled under a high voltage security fence to steal equipment worth tens of thousands of dollars from a water treatment plant, Hamilton police say.
Ten bronze water pump tullets, which resemble propellors and weigh up to 200kg each, were taken from the Glenview plant in the raid.
Police believe they were then taken back through the tunnel under a concrete slab beneath the fence.
Inspector Karen Hendrikson says it was a professional and sophisticated job. It is likely more than one person is involved and they probably had a vehicle close by.
The thieves would have had to have prior knowledge, but there is no information to suggest it was an inside job, she says.