Police are warning farmers in East Yorkshire to be vigilant following a spate of thefts from farms overnight on Tuesday.
Farms in the Holderness area were targeted late on Tuesday night and into the early hours of Wednesday morning.
Humberside Police is warning farmers in the area to be on their guard.
PCSO Darren Bainton from the Rural and Wildlife Crime Team said: "Several farm vehicles have been targeted and their GPS systems have been stolen.
“It is understood the thieves across other police forces are monitoring farms for tractors fitted with domes on the top of their cabs – as this indicates a satnav will likely be inside.
“In Mappleton, thieves approached a farm and forced entry to the building, steeling two Trimble GPS systems and antenna from the New Holland tractors. The theft took place sometime between 9pm Tuesday and 10am Wednesday.
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“In Burstwick, around 4:15am four men with a crowbar and angle grinder are believed to have forced padlocks to gain entry to a farm outbuilding and removed items including a generator, a Makita Drill and tools. A quad bike was also started but left at the seen."
PCSO Bainton is now asking all rural communities in the East Riding to remain vigilant and support any suspicious activity to police.
He said: “GPS systems are becoming as essential for farmers and losing them, and the information they hold, can have a considerable effect on farm businesses.
“I am advising farmers to remove these units from their tractors and other farm machinery each night. Don’t leave them in a locked cab, as these can be broken into. We would also ask farmers to consider using property marking kits as an added security measure.”
Anyone with information can call police on 101.