Gardaí in Co Donegal are on high-alert after the theft and attempted thefts of diggers in recent days.
Officers fear the robberies are being carried out by a gang who could use them to steal ATMs from the county.
It follows the recent spate of ATM thefts across the North and in the border counties.
An attempt was made to steal a digger from a yard at Pearse Road in Letterkenny over the weekend.
The lock was broken and a windscreen smashed between 5pm on Saturday and 7.30am on Monday morning.
It follows the theft of a digger from a Donegal County Council yard in St Johnston recently.
The Hitachi 26U digger was loaded onto a trailer in the yard and driven away across the border towards Derry.
The €38,000 digger, which was rented from Watson Hire in Letterkenny, has still not been located.
Garda Sgt Eunan Walsh appealed to members of the public to be vigilant.
"Obviously we have to keep an open mind on these robberies or attempted robberies because of the recent spate of thefts of ATMs.
"The latest attempt to steal a digger happened in Letterkenny over the weekend when a machine parked beside the Letterkenny Community Centre was interfered with.
"We're not sure if this is in any way connected with these ATM thefts but we have to consider all options," he said.
He appealed to members of the public who notice specific behaviour late at night to contact Gardai.
"If someone is out late at night and they spot a digger being towed at three or four o'clock in the morning then we would ask them to contact us.
"This would be unusual. It might not be anything but we will investigate it and it is better to be safe than sorry," he said.
Local Gardai are also liaising with bank employees in relation to best practise around ATMs.