Wanaka Police are blaming an increase in petrol prices for a "worrying trend" of fuel theft which is taking place in the resort.
Wanaka area commander Senior Sergeant Allan Grindell said four vehicles at a rental car company in Wanaka had been interfered with on Monday night.
Large quantities of fuel had been siphoned from the vehicles' petrol tanks, which had been forced open with a large screwdriver, he said.
"It is a worrying trend ... people need to be more vigilant about where they lave their vehicles and try, where possible, to observe prevention methods," he said.
A petrol tanker parked at a Mt Barker rural property had also been emptied of 400 litres of fuel recently, Snr Sgt Grindell said.
While the two incidents were not believed to be related, Snr Sgt Grindell said there had been an increasing number of reports of fuel being siphoned from parked vehicles at properties around the area.
"We suspect it might be the start of a big problem, especially if petrol prices keep rising," he said.
Police asked car owners to be vigilant and to report any suspicious behaviour, Snr Sgt Grindell said.
